This “Speed fix tool” sounds good, but is it for us?
Download El Capitan Cache Cleaner.
Start it up, click on “Demo”. It’s fully functional, and free.
Click on Cache Cleaning, and then do a deep cleaning of all caches.
When it says “Restart”, click “Cancel”.
Click on Maintenance, click on “All”, and then run.
When it is done, restart.
99% of the time, it is fixed. All zippy again.