Don't exactly understand extentPrecalculationPolicy

[mark8044]

For a sliver list with about 500 variable extent rows which are loaded via API pagination (item count keeps changing thus the list keeps rebuilding when new items are loaded and added), is it a good idea to use extentPrecalculationPolicy? Im not exactly understanding its purpose

I still get some jank when scrolling my lists and a rebuild happens with new data which id love to get rid of (I blame flutter for the Jank--- not this package, but was hoping this package could help on that front)

Thank you