Why are my browsers suddenly so slow? And also games like minecraft?

I'm not sure if the two are related because this happened around the same time. I use chrome and firefox. One day out of nowhere they started getting really slow. Firefox will sometimes freeze the moment it is opened. They are generally just slow at performing tasks that would be near instant before.

Minecraft is also horrendous to play now. I literally can't even turn around in the game without experiencing a lag spike. The worst thing is that if I exit the game, it will crash and then won't close! This is happening every time now! It used to be so smooth.

The only things I have done recently is uninstall advanced system care and switch it to avast. I have since uninstalled avast. I found that it was too interfering, but uninstalling it did not change anything so that probably isn't it. I have also downloaded ccleaner but that is a great piece of software so I kept that.

I just can't think what is causing this. Any ideas? Thanks

(please don't simply advise to delete my browser history. Ccleaner takes care of that)

Avast needs overhead to work, and if there's any programs it doesn't get along with it will build up a lot memory trying to monitor those programs. Use your task manager to see what programs are using extra memory.

Restore your system to a date before it was slow.