Re: Extremely slow when using relativenumber & syntax highlighting

On Thursday, March 27, 2014 7:13:06 AM UTC-4, Bram Moolenaar wrote:
> Dominique Pelle wrote:
>
>
>
> > patrick hemmer wrote:
>
> >
>
> > > Whenever I have relative line number on (relativenumber), and
>
> > > syntax highlighting enabled (syntax on), moving the cursor is
>
> > > painfully slow. Not only moving between lines, but just moving
>
> > > the cursor left/right on the same line.
>
> > >
>
> > > I've tried removing my local .vim & .vimrc files as well as the
>
> > > ones in /etc to have a completely default config. As soon as
>
> > > I `syntax on` and `set rnu`, it starts exhibiting the issue.
>
> > >
>
> > > It doesn't seem to do this on all files though, just most. As a
>
> > > reliable way to duplicate the issue, I can copy the http://yaml.org
>
> > > web page content into a .yaml file, and edit that.
>
> > > But I get it in multiple languages, perl, yaml, ruby, & other.
>
> > >
>
> > > Version 7.4 with patches 1-193 (though I've had this behavior for
>
> > > years with older versions).
>
> >
>
> > I can reproduce the slowness using the yaml file copied
>
> > from http://yaml.org
>
> >
>
> > Here are some timings with and without relativenumber
>
> > when moving 50 times horizontally with l and h:
>
> >
>
> > $ time vim -u NONE foo.yaml \
>
> > -c 'set relativenumber' \
>
> > -c 'syntax on' +10 \
>
> > -c 'call feedkeys("llllllllllhhhhhhhhhhllllllllllhhhhhhhhhhllllllllll:q\<CR>")'
>
> > real 0m4.677s
>
> > user 0m1.447s
>
> > sys 0m3.226s
>
> > --> slow!
>
> >
>
> > $ time vim -u NONE foo.yaml \
>
> > -c 'set norelativenumber' \
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> > -c 'syntax on' +10 \
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> > -c 'call feedkeys("llllllllllhhhhhhhhhhllllllllllhhhhhhhhhhllllllllll:q\<CR>")'
>
> > real 0m0.166s
>
> > user 0m0.086s
>
> > sys 0m0.077s
>
> > --> fast
>
> >
>
> > If I use ":syntime on" and ":syntime report", I see this:
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> >
>
> > With relativenumber:
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> >
>
> > TOTAL COUNT MATCH SLOWEST AVERAGE NAME PATTERN
>
> > 3.706423 7752 7395 0.002521 0.000478 yamlPlainScalar
>
>
>
> [...]
>
>
>
> >
>
> > Without relative number:
>
> >
>
> > TOTAL COUNT MATCH SLOWEST AVERAGE NAME PATTERN
>
> > 0.071678 152 145 0.001796 0.000472 yamlPlainScalar
>
>
>
> [...]
>
>
>
> > So somehow regexp are being checked far more often
>
> > when relativenumber is on, which does not seem right
>
> > considering that the command mostly moves horizontally.
>
> >
>
> > Using callgrind, I see that:
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> > * with 'norelativenumber', update_screen() was called only once
>
> > * with 'relativenumber', update_screen() was called 51 times
>
> >
>
> > Notice that the command I used was moving:
>
> > - 50 times horizontally with h and l
>
> > - 1 time vertically using +10
>
> >
>
> > This means that with relativenumber, update_screen() gets
>
> > called each time we move horizontally with h or l which does
>
> > not seem needed at first sight.
>
> >
>
> > The code that seems responsible for the spurious redraw is:
>
> > move.c:1190 (commenting that line as a experiment makes it fast)
>
> > so the logic to decide whether to redraw is wrong but I can't see
>
> > how to fix it:
>
> >
>
> > 1175 /* Redraw when w_row changes and 'relativenumber' is set */
>
> > 1176 if (((curwin->w_valid & VALID_WROW) == 0 && (curwin->w_p_rnu
>
> > 1177 #ifdef FEAT_SYN_HL
>
> > 1178 /* or when w_row changes and 'cursorline' is set. */
>
> > 1179 || curwin->w_p_cul
>
> > 1180