And Time Machine

and Time Machine are both terrific features, but they can cause performance issues, particularly if you backup to a network drive or allow Spotlight to index an external volume. To stop Spotlight indexing an external disk, go to the Spotlight pane in System Preferences and click on the Privacy tab. Drag the volume into the window or press ’+’ and select it. If Time Machine is slowing you down, you can pause a back-up while you get on with work. If it's a regular occurrence, consider using a local external drive as a back-up destination. and so rebooting regularly can have performance benefits. Also, modern Macs, especially those with SSD drives, boot almost as quickly as they wake from Sleep. If your Mac is running slowly, restart and see if that helps. Now resolve to restart once every few days.