I installed #Signal and #Conversations_im on a clean install of #GrapheneOS on my Pixel 4a and measured the battery impact. The results are shocking!
Both messengers had only one contact: my regular phone.
I used my regular phone to send messages to the Pixel 4a (which was not used for anything else over the course of the experiment).
I always sent the same message via Signal and #XMPP (mixing up which app went first). In total I sent ~32 messages in intervals of 10mins to a few hours.
@daniel As mentioned by Moritz @preya, #signal/ @signalapp shows no progress, interest or even involvement in getting this long standing issue fixed (https://github.com/signalapp/Signal-Android/issues/9729).
The community helped themselves and created an alternative Signal client, which is #molly (https://molly.im/) @mollyim
Molly uses #UnifiedPush and @S1m created a couple of battery saving apps, that handle notifying the molly-app to wake up and fetch the message.
So, use Molly instead. It could be cut off at anytime if signal decides to do so, until then it is a viable solution.