The problem starts when you swipe them away every few minutes. Each time you reopen them, your phone has to reload all the data, restart background processes, and redraw the interface. That "fresh ...
Android typically forces low-priority apps to sleep so that they don't drain your phone's battery. Putting apps to sleep means they won't consume a lot of power and won't run in the background ...
I revoked all the unnecessary app permissions from the Permission manager menu. For sensitive permissions, I switched to Ask ...