Here's one repro:
emacs -Q --eval "(tool-bar-mode -1)" --eval "(menu-bar-mode -1)" --eval
"(scroll-bar-mode -1)" --eval "(global-set-key \"a\" (lambda ()
(interactive) (find-file \"test.c\")))"
Where "test.c" is the name of a file in the current dir. Different files
can work, but for some the repro doesn't happen, like those, apparently,
which start with a paren (which makes show-paren-mode trigger its own
redisplay).
So, to repro:
- Run the command above
- Press "a"
- Look for the delay between the title bar and the window updates
With the above 'emacs -Q' it's not as prominent as with my config, but
it can reach what looks like 100-200ms. Once every 10 tries or so.