Consider using DwarFS

https://github.com/mhx/dwarfs is making bold claims:

> So in this comparison, mkdwarfs is **more than 6 times faster** than mksquashfs, both in terms of CPU time and wall clock time.
> In terms of compression ratio, the DwarFS file system is **more than 10 times smaller** than the SquashFS file system.

It'd be interesting to do some real-world comparisons by recompressing existing AppImages in DwarFS.

Reference:
* https://github.com/Phantop/appdwarf