See Patch Notes:
This update is a complex update, But the TLDR: It go faster but might break

• Added a precache system, This should cache systems and complex structures BEFORE it generates allowing for it to be accessed faster / instant Between a 5-15% performance bump
• Enhanced the speed of lots of the noise algorithms (10-15% performance bump)
• 3x'd the cache / load times for a 1-2x performance bump
• No more Object Drift
• No more Seed Drift
• No more Color Drift
• no more Color, Seed, Biome mismatches
• Fixed Memory leak post pregen when exploring

Speed Examples: (your results may vary)
PREGEN-
Before : 7-15cps
now: 40-250 (in spots)
WALKING ABOUT-
Before: 2-13
now: 30-80


So yea, Lots of updates.
THIS WILL LIKELY BREAK YOUR WORLD IF YOU ARE ON 2.2.17 specifically** . If you are on other versions the update will be less problematic, but some issues may happen, a regen is suggested
This is Experimental and you should make a backup before staying on this version as there will maybe be bugs, but to get them fixed we need them reported!

Git link:
https://github.com/VolmitSoftware/Iris/releases/tag/2.2.19-1.19.2