On 8/15/2020 11:07 AM, Achim Gratz wrote:
Ken Brown via Cygwin-announce writes:
The following packages have been uploaded to the Cygwin distribution:
* emacs-27.1-1
* emacs-common-27.1-1
* emacs-X11-27.1-1
* emacs-w32-27.1-1
* emacs-lucid-27.1-1
This release seems to have a serious performance regression when using
diff-mode on large diffs with long lines (e.g. created by comparing the
logs of two compilations), especially when combined with
toggle-truncate-lines. Emacs becomes unresponsive with 100% CPU load
when scrolling fast, sometimes for several seconds. The CPU time seems
to be spent in redisplay().
emacs has long had problems with slow redisplay in files with long lines. See,
for example,
https://debbugs.gnu.org/cgi/bugreport.cgi?bug=13675
and all the bugs that have been merged with it. One suggestion I've seen
recently is to try so-long-mode. Does that help?
Do you have reason to think this is Cygwin-specific? If so, it might be related
to the new pty code. Does it help to set CYGWIN=disable_pcon before starting
any Cygwin processes? (*)
Finally, does it matter which version of the emacs binary you use (emacs-w32,
emacs-X11,...)?
Ken
(*) Alternatively, if you don't mind building your own cygwin1.dll, you could
try Takashi's new version of the pty code:
https://cygwin.com/pipermail/cygwin-developers/2020-August/011941.html
I've seen dramatic speedups with this patch installed, though not specifically
with emacs.
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