Slow or lagging computer???
If you’re lucky, your problem is a software problem that can be easily resolved by running a repair utility or uninstalling and reinstalling if it’s a desktop app or logging off and on again if it’s a cloud app.
To keep problems away, keep your software updated. To keep your computer clean and in good shape, pay attention when things seem weird so you can start troubleshooting before it ruins your day. If you get a new computer and it’s having problems already — quick, trade it in while you still can.