Dear os-prober maintainers, there is an issue with update-grub and os-prober being very slow which seems to result from the use of grub-mount when searching for the data to identify the system and whatever else is required. You can mount a partition with grub-mount then copy some files and compare with regular mount, it's vastly slower, and even more so when using non-standard filesystems like BTRFS instead of EXT4. This means it can take minutes to complete update-grub rather than seconds. https://forum.artixlinux.org/index.php/topic,6818.msg41493 https://lists.gnu.org/archive/html/bug-grub/2024-05/msg00005.html
Perhaps it would be possible to run a test to see if regular mount is available and use that instead, or use some other FUSE implementation if it was required for security reasons? Reducing the amount of files searched would help, but if a full speed mount was used there should only be tiny fractions of a second involved rather than minutes, the grub-mount usage seems to be the root cause of the delays. Best wishes and thank you for maintaining os-prober, it's much easier than writing grub entries by hand!
