Saucemula, first - get rid of any apps that "boost" the device, the RAM, the battery or anything like that, Uninstall them! (This goes double for any apps written by Cheetah Mobile.)
Second, when you quit an app, use the back button, not the home button. I know you'll see all sorts of Youtubers using the Home button, but that just runs the launcher - the app that you were using keeps running in the background. There's a big difference between an app being in the background (there should always be a lot of those - unused RAM is wasted RAM in Android - it's not Windows) and an app running in the background. That degrades performance and slows the phone down. Open Recents (the square button at the bottom right), find the X in the upper right corner of each app other than the one you're currently running, and tap it. That will close most apps. And in the future, use the Back button when you're finished using an app.
See if those 2 things don't help.
(And don't try "boosting" a phone's performance - Android already does all the things those apps claim to do - without having an extra app running.)