Catalina has slowed my MacBook Pro

Many people have found that doing an SMC reset after upgrading to Catalina restores normal operation. See this Apple article:

How to reset the System Management Controller (SMC) on your Mac - Apple Support

Note that you must use the instruction set for your specific Mac model. Newer MacBook Pros with the T2 security chip have a different SMC reset procedure than older models.

If you are not sure which MBP sub-model you have, do "About this Mac..." from your Apple menu and find sub-molde information in the resulting window:

If you are still not sure, tell us the sub-model and we can help you figure out what SMC reset instructions to use.

After upgrading my MacBook Pro mid 2012 to Catalina it slowed to a crawl. Opened activity monitor and noticed my anti virus software was not responding (Trend Micro). After quitting the app the system worked normally. My Trend Micro anti virus was up to date and couldn’t find anything on Trend micro website for a fix. I’ll be looking for a Mac compatible anti virus app that runs on Catalina but this seems to have been the culprit.

You don't need an anti-virus program. There are no virus to detect.

My 2012 MBP runs like a champ and boots up faster than ever on Catalina. Your reversion to Mojave could have been avoided. But if you think that is the solution, well it's your thread.