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Subject: |
Re: 24.0.96-mac-2.92; Strange speed problem scrolling in C++ code |
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Date: |
Wed, 23 May 2012 02:24:49 -0500 |
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User-agent: |
Gnus/5.130006 (Ma Gnus v0.6) Emacs/24.0.97 (darwin) |
>>>>> YAMAMOTO Mitsuharu <address@hidden> writes:
> With the Time Profiler in Instrument.app, I found that fontification
> of CC Mode in Emacs 24 is much heavier and causes frequent GCs than
> that in Emacs 23. Please try the following:
>
> 1. Start Emacs 24 Mac port with -Q (alternatively, pressing the
> shift key.)
> 2. M-x load-file PREFIX/share/emacs/23.4/lisp/progmodes/cc-fonts.elc
> RTE.
> 3. Replay scrolling a large C++ file.
>
> I'm not sure if this slowdown is intended or expected.
Indeed, this makes the speed situation much better on Emacs 24.0.97.
- When I scroll a large C++ file in Emacs 24.0.97 the first time, the
performance is very choppy, even on a powerful Mac Pro machine.
There are moments toward the end of the file when I can actually count out
10 seconds or so before it moves on to the next page. The file is 17,983
lines long, consisting entirely of type declarations, enum, #define's and
prototypes.
- If I press M-<, go back to the top of the file, and then scroll to the
bottom again, there are basically no pauses.
- If I delete the buffer and re-open the file, scrolling is the same as
before.
- If I delete the buffer and load cc-fonts.elc from Emacs 23.4, scrolling
performance is *much* better. It is less choppy, and although it still
shows one long pause toward the end (garbage collection?), that's it.
- As before, going to the top with M-< and re-scrolling shows perfect speed,
no lag whatsoever; and killing the buffer and re-scrolling shows the same
faster performance as before, with less lag (but still a little bit).
The strange thing is, cc-fonts.el.gz is identical between Emacs 23.4 and Emacs
24.0.97! Only the .elc's differ. Have we found a byte-compilation issue in
Emacs 24?
John
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Subject: |
Re: 24.0.96-mac-2.92; Strange speed problem scrolling in C++ code |
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Date: |
Sat, 02 Nov 2019 12:08:47 +0100 |
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User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/27.0.50 (gnu/linux) |
Hi Alan,
Alan Mackenzie <address@hidden> writes:
>> Just to follow up on this bug, which has seen no update in the last 7
>> years. Has it been fixed by now?
>
> "Fixed" doesn't seem the right term, really. There have been several
> improvemnts in the scrolling speed over the years (the latest less than
> an hour ago ;-). When I scroll through a typical ~700k C++ buffer, I now
> experience mild sluggishness, a C-v taking a small fraction of a second,
> but longer than instantaneous. This is perhaps less than ideal on a
> slowish machine (which mine is not), but there's a tradeoff between rapid
> fontification and correct fontification.
>
> I think this bug should now be closed.
Thanks for that explanation. I'm consequently closing the bug.
Best regards,
Stefan Kangas
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