I'd identify the particular app that's causing your issues; instead of mass clearing out the recents list, or rebooting, slowly signal to the OS that you're don

I'd identify the particular app that's causing your issues; instead of mass clearing out the recents list, or rebooting, slowly signal to the OS that you're done with each app, one at a time, and determine whether your phone continues to run hot and drain battery after each closure. Eventually you'll narrow it down to the app with background privileges that's causing you grief. Kick that app off your phone, or otherwise stop running it. If you can't live without it, then the next time your battery life goes to hell, go into the recents list and remove only the troublesome app in question, so that the OS knows you're done with it and kills its (presumably crashed or busy-looping) background thread. Desist worrying about how many apps are in your recents list in general, because that's not a really related to the underlying problems you're experiencing.