patch 8.1.1922: in diff mode global operations can be very slow
Problem: In diff mode global operations can be very slow.
Solution: Do not call diff_redraw() many times, call it once when redrawing.
And also don't update folds multiple times.
diff --git a/src/fold.c b/src/fold.c
index 482d3c9..6200578 100644
--- a/src/fold.c
+++ b/src/fold.c
@@ -813,6 +813,11 @@
if (disable_fold_update > 0)
return;
+#ifdef FEAT_DIFF
+ if (need_diff_redraw)
+ // will update later
+ return;
+#endif
/* Mark all folds from top to bot as maybe-small. */
(void)foldFind(&wp->w_folds, top, &fp);