bug#17837: 24.4.50; Search very slow

[Eli Zaretskii]

> Date: Wed, 25 Jun 2014 07:28:53 -0400
> From: Richard Stallman <rms@gnu.org>
> CC: 17837@debbugs.gnu.org
> 
> However, there is no need to try more cases.
> Once there is one case that reproducibly causes bad behavior,
> using a debugger to figure out what happens in that case
> gives the lowest expected time to understanding the problem.

There's no need to debug this, because the reason is painfully clear:
once JIT font-lock kicks in (as a side effect of displaying a new
screenful of data), it takes it sufficiently long time to fontify the
displayed text.  As long as it fontifies, Emacs doesn't return to the
main loop, and your input is not obeyed.

The things I suggested were meant to provide some workaround for you,
not to solve the root cause (which AFAIU cannot be solved until HTML
fontification is this heavy).