os-prober slow, grub-mount results in very slow file transfers

[stratus--- via Bug reports for the GRand Unified Bootloader]

Dear Grub maintainers, myself and others on the Artix forum have experienced 
problems with os-prober running very slowly. The issue seems to occur in other 
distros as well, and the same subject has come up before in the past:
https://forum.artixlinux.org/index.php/topic,6818.msg41493
It appears that grub-mount uses a FUSE mount which requires a specific 
implementation for different filesystems. When the partitions are mounted with 
grub-mount, file reading operations are vastly slower than when mounted by the 
normal mount command. This is even worse on BTRFS than with EXT4, and it looks 
like NTFS is probably very slow too. This can be easily tested by using 
grub-mount to mount a partition then seeing how long it takes to copy some 
files over compared with a normal mount. And to further obscure the issue, it 
also appears to depend on how much searching os-prober has to do before  
finding out the information it needs, some distros like Devuan seem to yield 
this quickly so there still isn't any real delay, but Arch takes much longer 
and probably Windows too it appears.
I sometimes use gvfs-gphoto2 to transfer pictures and videos (some of which may 
be several GB in size) from my camera which uses a FUSE implementation and that 
doesn't have especially slow transfer speeds.
I wonder if you might be able to fix this sometime, or if you think the issue 
lies outside of grub, provide advice on who to "bug" about this instead.
Best wishes!