Re: bug-reference-prog-mode slows down CC Mode's scrolling by ~7%

[Stefan Monnier]

> To see the "waste" in single-windowful scrolls, we need a suitable
> benchmark, which measures the time of each scroll separately.  It
> would probably make sense to make it generate a random value of point,
> then measure the time it takes to go there and display.

Maybe a good way to see the waste is to measure the time for the initial
font-lock in an outline-mode buffer where the screen is filled with
single-line headers and everything else is hidden: a whole chunk will be
fontified for each line, so with a single 40-line screen you can expect
to fontify 40 chunks (unless the hidden text between lines is smaller
than the chunk size, of course).


        Stefan


PS: For the record, I was made aware of this case back in the days of
lazy-lock because lazy-lock didn't know how to skip invisible text (it
just fontified everything between window-start and window-end), so in
some cases it would end up fontifying the whole buffer.