Should I run an anti-virus scan to speed up my PC?

No, running an anti-virus scan will not necessarily speed up your PC. It can help to detect malicious software which may be slowing down your PC, but if you have already installed and updated an anti-virus program then scanning should not affect your PC’s speed. If you want to speed up your PC, you should try a few other things such as clearing out temporary files, disabling unneeded programs in startup, or upgrading your hardware.