As the name implies, rdiff-backup uses the rdiff method (more exactly, the reimplementation of rsync within librsync) to compute the differences between file versions.

gzip compression of increment files can be disabled with --no-compression after the backup flag.

Specifying --no-fsync will disable fsync, causing a significant speedup, with an elevated risk of data loss.

This is mostly due to their implementation as FUSE module, causing delays in certain operations, making it probably unfit for backup purposes.

Then, using touch, the modification time of all problematic files can be reset to now, and thus, they will be included during the next rdiff-backup run.