I changed mine to disable background data usage (although it only used 20 MB of background data) and the power usage from activity-based to optimized. It used 40% of the battery! But I don't think these changes will help much. It's the a version that didn't gobble up so much data?

I also asked some nostr devs about an interapplication nostr cache, if that's even possible on Android due to its security model.