Install from scratch only way to avoid slow Catalina

2014 Macbook Air 4GB 512GB SSD

A. If I install Catalina from scratch and copy all my files manually. It works fine. Everything is fast and smooth.

B. If I upgrade an Mojave Volume to Catalina. UI is painfully slow and fan spins up often. Seems related to file system access time.

C. If I take A and Carbon Copy Cloner to another volume in the same SSD (Had to do this to reclaim all my drive from 2 osx volumes) Same slow behavior as B.

Everything is APFS. I thought case B and C might be search indexing but seems to not improve after a few hours. Case A basically gets up and running smoothly pretty fast.