Right now the frames are saved with LZF compression over
frame differences. It makes compression ratio about 10x
times higher, but the speed (of LZF decompression) is still
rather slow.

A FullHD frame (1920x1080) is decompressed in about 16ms, which
is fine, but if the user creates a 6k image, then playback will
simply be impossible, because LZF compression will take about
60ms of time.