Many problems clear with a proper restart, and security updates only finish when the computer restarts.
Restart, do not just shut down
Choose Start, then the power button, then Restart. On most computers "Shut down" does not fully clear the system, so a restart is better when something is misbehaving.
Once a week
Restart your computer at least once a week, ideally at the end of the day so updates can finish.
When updates are waiting
If you see "Update and restart", save your work and choose it. Do not turn the computer off while it says updates are being installed, even if it seems slow.
Still slow after a restart?
Message us. We can see whether updates are stuck or something else is wrong.