OK, I did a better search and found something relevant in the fricken Matrix FAQ: * https://matrix.org/docs/guides/faq.html#i-installed-riot-via-f-droid-why-is

OK, I did a better search and found something relevant in the fricken Matrix FAQ: * https://matrix.org/docs/guides/faq.html#i-installed-riot-via-f-droid-why-is-it-draining-my-battery https://matrix.org/docs/guides/faq.html#i-installed-riot-via... >I installed Riot via F-Droid, why is it draining my battery? >The F-Droid release of Riot does not use Google Cloud Messaging. This allows users that do not have or want Google Services installed to use Riot. >The drawback is that Riot has to pull for new messages, which can drain your battery. To counter this, you can change the delay between polls in the settings. Higher delay means better battery life (but may delay receiving messages). You can also disable the background sync entirely (which means that you won’t get any notifications at all). >If you don’t mind using Google Services, you might be better off installing the Google Play store version.