Re: emacs rendering comparisson between emacs23 and emacs26.3

[Eli Zaretskii]

> From: Stefan Monnier <address@hidden>
> Cc: Eli Zaretskii <address@hidden>,  address@hidden,  address@hidden,
>   address@hidden,  address@hidden,  address@hidden
> Date: Sun, 05 Apr 2020 15:03:14 -0400
> 
> > What's the difference between redisplay being slow and it being unable to
> > "keep up"? I don't understand, sorry.
> 
> If there's already input waiting (because the next event already
> arrived) at the start of redisplay, then redisplay is short-circuited.

Only if you call 'redisplay' from Lisp explicitly.

"Normal" redisplay will probe pending input when it is going to send
the output to the glass, and will not do so if redisplay-don't-pause
is set to nil and there's input available.  IOW, whether input
available is checked not at the start of redisplay, but somewhere in
its middle.