diff --git a/src/testdir/crash/ex_redraw_crash b/src/testdir/crash/ex_redraw_crash
deleted file mode 100644
index eda294c..0000000
--- a/src/testdir/crash/ex_redraw_crash
+++ /dev/null
Binary files differ
diff --git a/src/testdir/runtest.vim b/src/testdir/runtest.vim
index 429e750..c14f44e 100644
--- a/src/testdir/runtest.vim
+++ b/src/testdir/runtest.vim
@@ -265,6 +265,9 @@
   " buffers.
   %bwipe!
 
+  " Clear all children notifications in case there are stale ones left
+  let g:child_notification = 0
+
   " The test may change the current directory. Save and restore the
   " directory after executing the test.
   let save_cwd = getcwd()
diff --git a/src/testdir/screendump.vim b/src/testdir/screendump.vim
index 84b4864..744f2ab 100644
--- a/src/testdir/screendump.vim
+++ b/src/testdir/screendump.vim
@@ -52,14 +52,14 @@
   let filter = 'dumps/' . a:filename . '.vim'
   let testfile = 'failed/' . a:filename . '.dump'
 
-  let max_loops = get(a:options, 'wait', 1000) / 10
+  let max_loops = get(a:options, 'wait', 1000) / 1
 
   " Starting a terminal to make a screendump is always considered flaky.
   let g:test_is_flaky = 1
   let g:giveup_same_error = 0
 
   " wait for the pending updates to be handled.
-  call TermWait(a:buf)
+  call TermWait(a:buf, 0)
 
   " Redraw to execute the code that updates the screen.  Otherwise we get the
   " text and attributes only from the internal buffer.
@@ -80,8 +80,8 @@
 
   let i = 0
   while 1
-    " leave some time for updating the original window
-    sleep 50m
+    " leave a bit of time for updating the original window while we spin wait.
+    sleep 1m
     call delete(testfile)
     call term_dumpwrite(a:buf, testfile, a:options)
 
diff --git a/src/testdir/shared.vim b/src/testdir/shared.vim
index 8ae6fa0..f459d87 100644
--- a/src/testdir/shared.vim
+++ b/src/testdir/shared.vim
@@ -136,6 +136,34 @@
   endif
 endfunc
 
+" Callback function to be invoked by a child terminal job. The parent could
+" then wait for the notification using WaitForChildNotification()
+let g:child_notification = 0
+func Tapi_notify_parent(bufnum, arglist)
+  let g:child_notification = 1
+endfunc
+
+" Generates a command that we can pass to a terminal job that it uses to
+" notify us. Argument 'escape' will specify whether to escape the double
+" quote.
+func TermNotifyParentCmd(escape)
+  call assert_false(has("win32"), 'Windows does not support terminal API right now. Use another method to synchronize timing.')
+  let cmd = '\033]51;["call", "Tapi_notify_parent", []]\007'
+  if a:escape
+    return escape(cmd, '"')
+  endif
+  return cmd
+endfunc
+
+" Wait for a child process to notify us. This allows us to sequence events in
+" conjunction with the child. Currently the only supported notification method
+" is for a terminal job to call Tapi_notify_parent() using terminal API.
+func WaitForChildNotification(...)
+  let timeout = get(a:000, 0, 5000)
+  call WaitFor({-> g:child_notification == 1}, timeout)
+  let g:child_notification = 0
+endfunc
+
 " Wait for up to five seconds for "expr" to become true.  "expr" can be a
 " stringified expression to evaluate, or a funcref without arguments.
 " Using a lambda works best.  Example:
@@ -162,7 +190,7 @@
 " A second argument can be used to specify a different timeout in msec.
 "
 " Return zero for success, one for failure (like the assert function).
-func WaitForAssert(assert, ...)
+func g:WaitForAssert(assert, ...)
   let timeout = get(a:000, 0, 5000)
   if s:WaitForCommon(v:null, a:assert, timeout) < 0
     return 1
@@ -200,11 +228,11 @@
       call remove(v:errors, -1)
     endif
 
-    sleep 10m
+    sleep 1m
     if exists('*reltimefloat')
       let slept = float2nr(reltimefloat(reltime(start)) * 1000)
     else
-      let slept += 10
+      let slept += 1
     endif
   endwhile
 
diff --git a/src/testdir/term_util.vim b/src/testdir/term_util.vim
index 67b21cb..19362aa 100644
--- a/src/testdir/term_util.vim
+++ b/src/testdir/term_util.vim
@@ -157,14 +157,14 @@
   call assert_equal("running", term_getstatus(a:buf))
 
   " Wait for all the pending updates to terminal to complete
-  call TermWait(a:buf)
+  call TermWait(a:buf, 1)
 
   " CTRL-O : works both in Normal mode and Insert mode to start a command line.
   " In Command-line it's inserted, the CTRL-U removes it again.
   call term_sendkeys(a:buf, "\<C-O>:\<C-U>qa!\<cr>")
 
   " Wait for all the pending updates to terminal to complete
-  call TermWait(a:buf)
+  call TermWait(a:buf, 1)
 
   " Wait for the terminal to end.
   call WaitForAssert({-> assert_equal("finished", term_getstatus(a:buf))})
diff --git a/src/testdir/test_balloon.vim b/src/testdir/test_balloon.vim
index 80d5831..3db37a7 100644
--- a/src/testdir/test_balloon.vim
+++ b/src/testdir/test_balloon.vim
@@ -36,6 +36,7 @@
   call TermWait(buf, 50)
   call term_sendkeys(buf, 'll')
   call term_sendkeys(buf, ":call Trigger()\<CR>")
+  sleep 150m " Wait for balloon to show up (100ms balloondelay time)
   call VerifyScreenDump(buf, 'Test_balloon_eval_term_01', {})
 
   " Make sure the balloon still shows after 'updatetime' passed and CursorHold
diff --git a/src/testdir/test_crash.vim b/src/testdir/test_crash.vim
index c83ddf2..85b1290 100644
--- a/src/testdir/test_crash.vim
+++ b/src/testdir/test_crash.vim
@@ -4,11 +4,15 @@
 
 CheckScreendump
 
+" Run the command in terminal and wait for it to complete via notification
+func s:RunCommandAndWait(buf, cmd)
+  call term_sendkeys(a:buf, a:cmd .. "; printf '" .. TermNotifyParentCmd(v:false) .. "'\<cr>")
+  call WaitForChildNotification()
+endfunc
+
 func Test_crash1()
   CheckNotBSD
   CheckExecutable dash
-  " Test 7 fails on Mac ...
-  CheckNotMac
 
   " The following used to crash Vim
   let opts = #{cmd: 'sh'}
@@ -19,70 +23,59 @@
   let file = 'crash/poc_huaf1'
   let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'"
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ '  && echo "crash 1: [OK]" > X_crash1_result.txt' .. "\<cr>")
-  call TermWait(buf, 50)
+  call s:RunCommandAndWait(buf, args ..
+    \ '  && echo "crash 1: [OK]" > X_crash1_result.txt')
 
   let file = 'crash/poc_huaf2'
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ '  && echo "crash 2: [OK]" >> X_crash1_result.txt' .. "\<cr>")
-  call TermWait(buf, 50)
+  call s:RunCommandAndWait(buf, args ..
+    \ '  && echo "crash 2: [OK]" >> X_crash1_result.txt')
 
   let file = 'crash/poc_huaf3'
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ '  && echo "crash 3: [OK]" >> X_crash1_result.txt' .. "\<cr>")
-  call TermWait(buf, 100)
+  call s:RunCommandAndWait(buf, args ..
+    \ '  && echo "crash 3: [OK]" >> X_crash1_result.txt')
 
   let file = 'crash/bt_quickfix_poc'
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ '  && echo "crash 4: [OK]" >> X_crash1_result.txt' .. "\<cr>")
+  call s:RunCommandAndWait(buf, args ..
+    \ '  && echo "crash 4: [OK]" >> X_crash1_result.txt')
   " clean up
   call delete('Xerr')
-  " This test takes a bit longer
-  call TermWait(buf, 1000)
 
   let file = 'crash/poc_tagfunc.vim'
   let args = printf(cmn_args, vim, file)
   " using || because this poc causes vim to exit with exitstatus != 0
-  call term_sendkeys(buf, args ..
-    \ '  || echo "crash 5: [OK]" >> X_crash1_result.txt' .. "\<cr>")
+  call s:RunCommandAndWait(buf, args ..
+    \ '  || echo "crash 5: [OK]" >> X_crash1_result.txt')
 
-  call TermWait(buf, 100)
 
   let file = 'crash/bt_quickfix1_poc'
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ '  && echo "crash 6: [OK]" >> X_crash1_result.txt' .. "\<cr>")
+  call s:RunCommandAndWait(buf, args ..
+    \ '  && echo "crash 6: [OK]" >> X_crash1_result.txt')
   " clean up
   call delete('X')
-  call TermWait(buf, 3000)
 
   let file = 'crash/vim_regsub_both_poc'
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ '  && echo "crash 7: [OK]" >> X_crash1_result.txt' .. "\<cr>")
-  call TermWait(buf, 3000)
+  call s:RunCommandAndWait(buf, args ..
+    \ '  && echo "crash 7: [OK]" >> X_crash1_result.txt')
 
   let file = 'crash/vim_msg_trunc_poc'
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ '  || echo "crash 8: [OK]" >> X_crash1_result.txt' .. "\<cr>")
-  call TermWait(buf, 3000)
+  call s:RunCommandAndWait(buf, args ..
+    \ '  || echo "crash 8: [OK]" >> X_crash1_result.txt')
 
   let file = 'crash/crash_scrollbar'
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ '  && echo "crash 9: [OK]" >> X_crash1_result.txt' .. "\<cr>")
-  call TermWait(buf, 1000)
+  call s:RunCommandAndWait(buf, args ..
+    \ '  && echo "crash 9: [OK]" >> X_crash1_result.txt')
 
   let file = 'crash/editing_arg_idx_POC_1'
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ '  || echo "crash 10: [OK]" >> X_crash1_result.txt' .. "\<cr>")
-  call TermWait(buf, 1000)
+  call s:RunCommandAndWait(buf, args ..
+    \ '  || echo "crash 10: [OK]" >> X_crash1_result.txt')
   call delete('Xerr')
   call delete('@')
 
@@ -113,7 +106,6 @@
 func Test_crash1_2()
   CheckNotBSD
   CheckExecutable dash
-  let g:test_is_flaky = 1
 
   " The following used to crash Vim
   let opts = #{cmd: 'sh'}
@@ -125,37 +117,32 @@
   let file = 'crash/poc1'
   let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'"
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ '  && echo "crash 1: [OK]" > '.. result .. "\<cr>")
-  call TermWait(buf, 150)
+  call s:RunCommandAndWait(buf, args ..
+    \ '  && echo "crash 1: [OK]" > '.. result)
 
   let file = 'crash/poc_win_enter_ext'
   let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'"
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ '  && echo "crash 2: [OK]" >> '.. result .. "\<cr>")
-  call TermWait(buf, 350)
+  call s:RunCommandAndWait(buf, args ..
+    \ '  && echo "crash 2: [OK]" >> '.. result)
 
   let file = 'crash/poc_suggest_trie_walk'
   let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'"
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ '  && echo "crash 3: [OK]" >> '.. result .. "\<cr>")
-  call TermWait(buf, 150)
+  call s:RunCommandAndWait(buf, args ..
+    \ '  && echo "crash 3: [OK]" >> '.. result)
 
   let file = 'crash/poc_did_set_langmap'
   let cmn_args = "%s -u NONE -i NONE -n -X -m -n -e -s -S %s -c ':qa!'"
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ ' ; echo "crash 4: [OK]" >> '.. result .. "\<cr>")
-  call TermWait(buf, 150)
+  call s:RunCommandAndWait(buf, args ..
+    \ ' ; echo "crash 4: [OK]" >> '.. result)
 
   let file = 'crash/reverse_text_overflow'
   let cmn_args = "%s -u NONE -i NONE -n -X -m -n -e -s -S %s -c ':qa!'"
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ ' ; echo "crash 5: [OK]" >> '.. result .. "\<cr>")
-  call TermWait(buf, 150)
+  call s:RunCommandAndWait(buf, args ..
+    \ ' ; echo "crash 5: [OK]" >> '.. result)
 
   " clean up
   exe buf .. "bw!"
@@ -181,64 +168,49 @@
   let buf = RunVimInTerminal('sh', #{cmd: 'sh'})
 
   let file = 'crash/poc_ex_substitute'
-  let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'\<cr>"
+  let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'"
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args)
-  call TermWait(buf, 150)
+  call s:RunCommandAndWait(buf, args)
 
   let file = 'crash/poc_uaf_exec_instructions'
-  let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'\<cr>"
+  let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'"
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args)
-  call TermWait(buf, 150)
+  call s:RunCommandAndWait(buf, args)
 
   let file = 'crash/poc_uaf_check_argument_types'
-  let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'\<cr>"
+  let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'"
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args)
-  call TermWait(buf, 150)
+  call s:RunCommandAndWait(buf, args)
 
   let file = 'crash/double_free'
-  let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'\<cr>"
+  let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'"
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args)
-  call TermWait(buf, 50)
+  call s:RunCommandAndWait(buf, args)
 
   let file = 'crash/dialog_changed_uaf'
-  let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'\<cr>"
+  let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'"
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args)
-  call TermWait(buf, 150)
+  call s:RunCommandAndWait(buf, args)
 
   let file = 'crash/nullpointer'
-  let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'\<cr>"
+  let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'"
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args)
-  call TermWait(buf, 50)
+  call s:RunCommandAndWait(buf, args)
 
   let file = 'crash/heap_overflow3'
   let cmn_args = "%s -u NONE -i NONE -n -X -m -n -e -s -S %s -c ':qa!'"
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args)
-  call TermWait(buf, 150)
+  call s:RunCommandAndWait(buf, args)
 
   let file = 'crash/heap_overflow_glob2regpat'
   let cmn_args = "%s -u NONE -i NONE -n -X -m -n -e -s -S %s -c ':qa!'"
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args)
-  call TermWait(buf, 50)
+  call s:RunCommandAndWait(buf, args)
 
   let file = 'crash/nullptr_regexp_nfa'
   let cmn_args = "%s -u NONE -i NONE -n -X -m -n -e -s -S %s -c ':qa!'"
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args)
-  call TermWait(buf, 50)
-
-  let file = 'crash/ex_redraw_crash'
-  let cmn_args = "%s -u NONE -i NONE -n -m -X -Z -e -s -S %s -c ':qa!'"
-  let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args)
-  call TermWait(buf, 150)
+  call s:RunCommandAndWait(buf, args)
 
   " clean up
   exe buf .. "bw!"
diff --git a/src/testdir/test_listlbr_utf8.vim b/src/testdir/test_listlbr_utf8.vim
index 693f201..bd0578e 100644
--- a/src/testdir/test_listlbr_utf8.vim
+++ b/src/testdir/test_listlbr_utf8.vim
@@ -370,6 +370,7 @@
 func Test_visual_ends_before_showbreak()
   CheckScreendump
 
+  " Redraw at the end is necessary due to https://github.com/vim/vim/issues/16620
   let lines =<< trim END
       vim9script
       &wrap = true
@@ -377,6 +378,7 @@
       &showbreak = '↪ '
       ['xxxxx ' .. 'y'->repeat(&columns - 6) .. ' zzzz']->setline(1)
       normal! wvel
+      redraw
   END
   call writefile(lines, 'XvisualEndsBeforeShowbreak', 'D')
   let buf = RunVimInTerminal('-S XvisualEndsBeforeShowbreak', #{rows: 6})
diff --git a/src/testdir/test_tagjump.vim b/src/testdir/test_tagjump.vim
index c241937..67bd95f 100644
--- a/src/testdir/test_tagjump.vim
+++ b/src/testdir/test_tagjump.vim
@@ -751,15 +751,15 @@
   call writefile(code, 'Xfoo', 'D')
 
   let v:statusmsg = ''
-  ta func1
+  silent ta func1
   call assert_match('E435:', v:statusmsg)
   call assert_equal(2, line('.'))
   let v:statusmsg = ''
-  ta func2
+  silent ta func2
   call assert_match('E435:', v:statusmsg)
   call assert_equal(4, line('.'))
   let v:statusmsg = ''
-  ta func3
+  silent ta func3
   call assert_match('E435:', v:statusmsg)
   call assert_equal(5, line('.'))
   call assert_fails('ta func4', 'E434:')
@@ -1625,7 +1625,7 @@
 
   let v:statusmsg = ''
   let @/ = ''
-  ta y
+  silent ta y
   call assert_match('E435:', v:statusmsg)
   call assert_equal(2, line('.'))
   call assert_match('<y', @/)
diff --git a/src/testdir/test_terminal.vim b/src/testdir/test_terminal.vim
index d3744fa..9dbdfda 100644
--- a/src/testdir/test_terminal.vim
+++ b/src/testdir/test_terminal.vim
@@ -60,8 +60,8 @@
   close
 
   if has("unix")
-    terminal ++hidden ++open sleep 1
-    sleep 1
+    terminal ++hidden ++open echo
+    call WaitForAssert({-> assert_equal('terminal', &buftype)})
     call assert_fails("echo b:done", 'E121:')
   endif
 
diff --git a/src/testdir/test_terminal2.vim b/src/testdir/test_terminal2.vim
index 5c4563c..542f2ec 100644
--- a/src/testdir/test_terminal2.vim
+++ b/src/testdir/test_terminal2.vim
@@ -292,11 +292,6 @@
 func Test_termwinscroll_topline2()
   " calling the terminal API doesn't work on Windows
   CheckNotMSWindows
-  let g:test_is_flaky = 1
-  let g:print_complete = 0
-  func! Tapi_print_complete(bufnum, arglist)
-    let g:print_complete = 1
-  endfunc
 
   set termwinscroll=50000 mouse=a
   set shell=sh
@@ -310,17 +305,15 @@
   let num1 = &termwinscroll / 1000 * 999
   call writefile(range(num1), 'Xtext', 'D')
   call term_sendkeys(buf, "cat Xtext\<CR>")
-  call term_sendkeys(buf, 'printf ''\033]51;["call", "Tapi_print_complete", []]\007''' .. "\<cr>")
+  call term_sendkeys(buf, "printf '" .. TermNotifyParentCmd(v:false) .. "'\<cr>")
   let rows = term_getsize(buf)[0]
   let cnt = 0
-  while !g:print_complete && cnt <= 1000
-    " max number of runs
+  while !g:child_notification && cnt <= 50000
+    " Spin wait to process the terminal print as quickly as possible. This is
+    " more efficient than calling WaitForChildNotification() as we don't want
+    " to sleep here as the print is I/O-bound.
     let cnt += 1
-    " sleep a bit, to give the the terminal some time to finish
-
-    " It may take a while to finish on a slow system
-    " so wait a bit and handle the callback
-    call term_wait(buf)
+    call term_wait(buf, 0)
   endwhile
   call WaitForAssert({-> assert_match(string(num1 - 1), term_getline(buf, rows - 1) .. '\|' .. term_getline(buf, rows - 2))})
   call feedkeys("\<C-W>N", 'xt')
@@ -347,8 +340,6 @@
 
   exe buf . 'bwipe!'
   set termwinscroll& mouse& sh&
-  delfunc Tapi_print_complete
-  unlet! g:print_complete
 endfunc
 
 " Resizing the terminal window caused an ml_get error.
diff --git a/src/testdir/test_terminal3.vim b/src/testdir/test_terminal3.vim
index 5865d18..0e5f70b 100644
--- a/src/testdir/test_terminal3.vim
+++ b/src/testdir/test_terminal3.vim
@@ -75,22 +75,30 @@
 
   let lines = [
 	\ 'call setline(1, range(20))',
+    \ 'func NotifyParent()',
+    \ '  call echoraw("' .. TermNotifyParentCmd(v:true) .. '")',
+    \ 'endfunc',
 	\ 'func OpenTerm()',
 	\ '  set noruler',
-	\ "  call term_start('cat', #{vertical: 1, " .. a:highlight_opt .. "})",
+	\ "  call term_start('cat', #{vertical: 1, "
+    \      .. 'exit_cb: {->NotifyParent()}, '
+    \      .. a:highlight_opt .. "})",
+    \ '  call NotifyParent()',
 	\ ] + a:open_cmds + [
 	\ 'endfunc',
-	\ ] + a:highlight_cmds
+	\ ] + a:highlight_cmds + [
+    \ 'call NotifyParent()',
+    \ ]
   call writefile(lines, 'XtermStart', 'D')
   let buf = RunVimInTerminal('-S XtermStart', #{rows: 15})
-  call TermWait(buf, 100)
+  call WaitForChildNotification()
   call term_sendkeys(buf, ":call OpenTerm()\<CR>")
-  call TermWait(buf, 50)
+  call WaitForChildNotification()
   call term_sendkeys(buf, "hello\<CR>")
   call VerifyScreenDump(buf, 'Test_terminal_color_' .. a:group_name, {})
 
   call term_sendkeys(buf, "\<C-D>")
-  call TermWait(buf, 50)
+  call WaitForChildNotification()
   call StopVimInTerminal(buf)
 endfunc
 
@@ -270,11 +278,11 @@
 	\ ]
   call writefile(lines, 'XtermPopup', 'D')
   let buf = RunVimInTerminal('-S XtermPopup', #{rows: 15})
-  call TermWait(buf, 200)
+  call TermWait(buf,0)
   call term_sendkeys(buf, ":call OpenTerm(0)\<CR>")
-  call TermWait(buf, 800)
+  call TermWait(buf,0)
   call term_sendkeys(buf, ":\<CR>")
-  call TermWait(buf, 500)
+  call TermWait(buf,0)
   call term_sendkeys(buf, "\<C-W>:echo getwinvar(g:winid, \"&buftype\") win_gettype(g:winid)\<CR>")
   call VerifyScreenDump(buf, 'Test_terminal_popup_1', {})
 
@@ -282,16 +290,16 @@
   call VerifyScreenDump(buf, 'Test_terminal_popup_2', {})
  
   call term_sendkeys(buf, ":call OpenTerm(1)\<CR>")
-  call TermWait(buf, 800)
+  call TermWait(buf,0)
   call term_sendkeys(buf, ":set hlsearch\<CR>")
-  call TermWait(buf, 500)
+  call TermWait(buf,0)
   call term_sendkeys(buf, "/edit\<CR>")
   call VerifyScreenDump(buf, 'Test_terminal_popup_3', {})
  
   call term_sendkeys(buf, "\<C-W>:call HidePopup()\<CR>")
   call VerifyScreenDump(buf, 'Test_terminal_popup_4', {})
   call term_sendkeys(buf, "\<CR>")
-  call TermWait(buf, 50)
+  call TermWait(buf,0)
 
   call term_sendkeys(buf, "\<C-W>:call ClosePopup()\<CR>")
   call VerifyScreenDump(buf, 'Test_terminal_popup_5', {})
@@ -307,9 +315,9 @@
   call term_sendkeys(buf, "A")
   call VerifyScreenDump(buf, 'Test_terminal_popup_8', {})
 
-  call TermWait(buf, 50)
+  call TermWait(buf,0)
   call term_sendkeys(buf, ":q\<CR>")
-  call TermWait(buf, 250)  " wait for terminal to vanish
+  call WaitForAssert({-> assert_equal(0, match(term_getline(buf, 6), '^5\s*$'))}, 250) " wait for terminal to vanish
 
   call StopVimInTerminal(buf)
 endfunc
@@ -353,27 +361,32 @@
 
   let lines = [
 	\ 'call setline(1, range(20))',
+    \ 'func NotifyParent(...)',
+    \ '  call echoraw("' .. TermNotifyParentCmd(v:true) .. '")',
+    \ 'endfunc',
 	\ 'func OpenTerm()',
-	\ "  let s:buf = term_start('cat', #{hidden: 1, "
+	\ "  let s:buf = term_start('cat', #{hidden: 1, term_finish: 'close', "
 	\ .. a:highlight_opt .. "})",
-	\ '  let g:winid = popup_create(s:buf, #{border: [], '
-  \ .. a:popup_opt .. '})',
-  \ ] + a:popup_cmds + [
+    \ '  let g:winid = popup_create(s:buf, #{border: [], '
+    \      .. 'callback: {->NotifyParent()}, '
+    \      .. a:popup_opt .. '})',
+    \ ] + a:popup_cmds + [
+    \ '  call NotifyParent()',
 	\ 'endfunc',
-	\ ] + a:highlight_cmds
+	\ ] + a:highlight_cmds + [
+    \ 'call NotifyParent()',
+    \ ]
   call writefile(lines, 'XtermPopup', 'D')
   let buf = RunVimInTerminal('-S XtermPopup', #{rows: 15})
-  call TermWait(buf, 100)
+  call WaitForChildNotification()
   call term_sendkeys(buf, ":set noruler\<CR>")
   call term_sendkeys(buf, ":call OpenTerm()\<CR>")
-  call TermWait(buf, 50)
+  call WaitForChildNotification()
   call term_sendkeys(buf, "hello\<CR>")
   call VerifyScreenDump(buf, 'Test_terminal_popup_' .. a:group_name, {})
 
   call term_sendkeys(buf, "\<C-D>")
-  call TermWait(buf, 50)
-  call term_sendkeys(buf, ":q\<CR>")
-  call TermWait(buf, 50)  " wait for terminal to vanish
+  call WaitForChildNotification()
   call StopVimInTerminal(buf)
 endfunc
 
diff --git a/src/testdir/test_timers.vim b/src/testdir/test_timers.vim
index 4bde75f..d2f621c 100644
--- a/src/testdir/test_timers.vim
+++ b/src/testdir/test_timers.vim
@@ -44,11 +44,15 @@
   let slept = WaitFor('g:val == 3')
   call assert_equal(3, g:val)
   if has('reltime')
+    " Timer has an internal 1ms allowance in calculating due time, so it's
+    " possible for each timer to undershoot by 1ms resulting in only 49*3=147
+    " ms elapsed. Additionally we started the timer before we called
+    " WaitFor(), so the reported time could be a couple more ms below 147.
     if has('mac')
-      " Mac on Travis can be slow.
-      call assert_inrange(149, 400, slept)
+      " Mac in CI can be slow.
+      call assert_inrange(145, 400, slept)
     else
-      call assert_inrange(149, 250, slept)
+      call assert_inrange(145, 250, slept)
     endif
   else
     call assert_inrange(80, 200, slept)
@@ -143,13 +147,13 @@
   # Another timer will fire in half a second and close it early after stopping
   # all timers.
   var pop = popup_create('Popup', {time: 10000})
-  var tmr = timer_start(500, (_) => {
+  var tmr = timer_start(100, (_) => {
     timer_stopall()
     popup_clear()
   })
-  sleep 1
+  sleep 100m
+  g:WaitForAssert(() => assert_equal([], popup_list()), 1000)
   assert_equal([], timer_info(tmr))
-  assert_equal([], popup_list())
 enddef
 
 func Test_timer_paused()
diff --git a/src/testdir/test_visual.vim b/src/testdir/test_visual.vim
index 03335a4..6c2ef59 100644
--- a/src/testdir/test_visual.vim
+++ b/src/testdir/test_visual.vim
@@ -1559,10 +1559,12 @@
 func Test_visual_hl_with_showbreak()
   CheckScreendump
 
+  " Redraw at the end is necessary due to https://github.com/vim/vim/issues/16620
   let lines =<< trim END
     setlocal showbreak=+
     call setline(1, repeat('a', &columns + 10))
     normal g$v4lo
+    redraw
   END
   call writefile(lines, 'XTest_visual_sbr', 'D')