Optimized residence cleaning process which involves defined block removal after residence got removed. Due to new method residence cleaning will only work on 1.13+ versions and option to enable this feature on older versions than that will not appear.
Same as previous change, optimized LWC protection removal which now is allot faster and mostly done in async. So you should not longer experience effect of removing huge residences. Same thing applies, this feature will be only available as of 1.13+ versions due to new more efficient way in checking blocks