patch 9.0.0948: 'ttyfast' is set for arbitrary terminals

Problem:    'ttyfast' is set for arbitrary terminals.
Solution:   Always set 'ttyfast'. (closes #11549)
diff --git a/runtime/doc/options.txt b/runtime/doc/options.txt
index c730527..83a4904 100644
--- a/runtime/doc/options.txt
+++ b/runtime/doc/options.txt
@@ -8569,10 +8569,7 @@
 	xterm entries...).
 
 				     *'ttyfast'* *'tf'* *'nottyfast'* *'notf'*
-'ttyfast' 'tf'		boolean	(default off, on when 'term' is xterm, hpterm,
-					sun-cmd, screen, rxvt, dtterm or
-					iris-ansi; also on when running Vim in
-					a DOS console)
+'ttyfast' 'tf'		boolean	(default on)
 			global
 	Indicates a fast terminal connection.  More characters will be sent to
 	the screen for redrawing, instead of using insert/delete line
@@ -8582,6 +8579,14 @@
 	line for lines that wrap.  This helps when using copy/paste with the
 	mouse in an xterm and other terminals.
 
+	The default used to be set only for some terminal names, but these
+	days nearly all terminals are fast, therefore the default is now "on".
+	If you have a slow connection you may want to set this option off,
+	e.g. depending on the host name: >
+		if hostname() =~ 'faraway'
+		   set nottyfast
+		endif
+<
 						*'ttymouse'* *'ttym'*
 'ttymouse' 'ttym'	string	(default depends on 'term')
 			global
diff --git a/runtime/doc/os_unix.txt b/runtime/doc/os_unix.txt
index 0b0f389..f875f16 100644
--- a/runtime/doc/os_unix.txt
+++ b/runtime/doc/os_unix.txt
@@ -28,10 +28,11 @@
 can be changed at compile time.
 (For forking of the GUI version see |gui-fork|.)
 
-Because terminal updating under Unix is often slow (e.g. serial line
-terminal, shell window in suntools), the 'showcmd' and 'ruler' options
-are off by default.  If you have a fast terminal, try setting them on.  You
-might also want to set 'ttyfast'.
+For historic reasons terminal updating under Unix is expected to be slow (e.g.
+serial line terminal, shell window in suntools), the 'showcmd' and 'ruler'
+options are off by default.  If you have a fast terminal, try setting them
+on: >
+	set showcmd ruler
 
 When using Vim in an xterm the mouse clicks can be used by Vim by setting
 'mouse' to "a".  If there is access to an X-server gui style copy/paste will
diff --git a/runtime/doc/os_vms.txt b/runtime/doc/os_vms.txt
index b2a1590..8ba12ba 100644
--- a/runtime/doc/os_vms.txt
+++ b/runtime/doc/os_vms.txt
@@ -458,18 +458,11 @@
 
 Vim will also recognize that they are fast terminals.
 
-If you have some annoying line jumping on the screen between windows add to
-your .vimrc file: >
-
-	set ttyfast	" set fast terminal
-
-Note: if you're using Vim on remote host or through a very slow connection, it's
-recommended to avoid the fast terminal option with: >
+If you're using Vim on remote host or through a very slow connection, you
+might want to reset fast terminal option with: >
 
 	set nottyfast   " set terminal to slow mode
 
-(Zoltan Arpadffy, Vim 5.6)
-
 
 8.7 Hex-editing and other external tools
 
diff --git a/runtime/doc/term.txt b/runtime/doc/term.txt
index fdbcc7d..2bd83c7 100644
--- a/runtime/doc/term.txt
+++ b/runtime/doc/term.txt
@@ -768,8 +768,9 @@
 
 If your terminal does not support a scrolling region, but it does support
 insert/delete line commands, scrolling with multiple windows may make the
-lines jump up and down.  If you don't want this set the 'ttyfast' option.
-This will redraw the window instead of scroll it.
+lines jump up and down.  This would happen if the 'ttyfast' option has been
+reset.  Check that with: >
+	verbose set ttyfast?
 
 If your terminal scrolls very slowly, but redrawing is not slow, set the
 'ttyscroll' option to a small number, e.g., 3.  This will make Vim redraw the