Bug#1125313: libc6: Performance regression in KDE/Qt apps after update to 2.41-12+deb13u1
Hi,
On 2026-01-12 12:15, chris wrote:
> Package: libc6
> Version: 2.41-12+deb13u1
> Severity: important
> X-Debbugs-Cc: alexsc.debian@gmail.com
>
> Dear Maintainer,
>
> After upgrading to glibc 2.41-12+deb13u1 (Debian 13.3 point release on
> January 10, 2026), all KDE/Qt applications experience severe startup
> delays of 1-3 seconds. Previously these applications started instantly.
>
> What led up to the situation:
> System was updated with 'apt upgrade' which included the glibc update
> from the 13.3 point release.
Have you been able to confirm the issue actually comes from this new
glibc version? For instance you can try downgrading it to version
2.41-12 and check it solves the issue.
> What exactly did you do:
> Tested multiple terminals and applications:
> - Konsole: 2-3 second startup delay
> - Alacritty: 1-2 second startup delay
> - Other Qt/KDE applications show similar slowdown
> - Non-Qt applications (xterm) start instantly
I have tried to reproduce the issue, but I haven't been able to so far.
Also looking at the change introduced in this new version, I haven't
been able to find an obvious culprit in the commit backported in this
version.
Could you please try to run any of the software having an issue under
strace and share the output? That could give a hint at what is wrong.
You might want to use the -tt option to get timestamp and the -o option
to save the log.
Regards
Aurelien
--
Aurelien Jarno GPG: 4096R/1DDD8C9B
aurelien@aurel32.net http://aurel32.net
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