patch 8.2.0397: delayed screen update when using undo from Insert mode Commit: https://github.com/vim/vim/commit/5715b3147bfc8ddfe905339f6fd224fd3a5a3ba1 Author: Bram Moolenaar <Bram@vim.org> Date: Mon Mar 16 22:08:45 2020 +0100 patch 8.2.0397: delayed screen update when using undo from Insert mode Problem: Delayed screen update when using undo from Insert mode. Solution: Update w_topline and cursor shape before sleeping. (closes https://github.com/vim/vim/issues/5790)

"Test for benchmarking the RE engine

so small.vim
if !has("reltime") | finish | endif
func! Measure(file, pattern, arg)
	for re in range(3)
	    let sstart=reltime()
	    let cmd=printf("../vim -u NONE -N --cmd ':set re=%d'".
		\ " -c 'call search(\"%s\", \"\", \"\", 10000)' -c ':q!' %s", re, escape(a:pattern, '\\'), empty(a:arg) ? '' : a:arg)
	    call system(cmd. ' '. a:file)
	    $put =printf('file: %s, re: %d, time: %s', a:file, re, reltimestr(reltime(sstart)))
	endfor
endfunc