I started “syncing” via GitHub a month or two ago because iCloud was taking an eternity to download files almost every time I opened the app. Moving to Git sync eliminated that part of the process, making syncing more reliable and startups much faster than with iCloud sync.
However, there is still something inherent to my vault that causes the iOS app to reindex it quite frequently. I haven’t figured out what’s causing that—it could just be that my phone is really old and won’t retain Obsidian in memory.