brush unresponsive, when I scroll the software lags before it allows me to zoom in on the project. Restarting the PC hasn't been working.
I'm sorry, but "lags" isn't a useful bug report. A bug report is about something in the code that we can fix, not problems specific to a particular setup. We don't know anything about your system... Here are a couple of things to try: https://docs.krita.org/KritaFAQ#Krita_is_slow