Much less data in the background.
- Checking for new messages in the background now uses far less data: the app holds the connection open longer instead of reconnecting constantly, and skips redundant lookups on secured chats.
- Roughly 50% less background data with the new Data saver off, and around 60% less with it on - on mobile data the saver also stops background update checks and eases off further when the connection drops.
- New setting in Settings -> Background data: Automatic (saves only on mobile data), Always, or Never.
- Messages stay end-to-end encrypted; only the checking overhead shrinks, so nothing about delivery changes.