I think I've used just about every custom ROM for Xperia X (even the treble ones) and I can safely say this is the most efficient one even more so than marshmallow ROMs. To give you an idea, I was able to run a 1080p YouTube video at 100% brightness for 2h30m before battery reached empty. Performance and smoothness is better than every Oreo based ROM with smoothness still present even in power saving mode. Great ROM.