I had nearly 9 months of very slow response times in Mojave but I suspected I needed to reinstall from scratch. I resisted doing so because I'd developed many dozens of dependencies that I didn't want to chase down (e.g. custom-compiled ImageMagick).
Doing the dreaded "clean install" fixed my issues (primarily a Finder that would routinely spend up to 30 seconds or more displaying the contents of any folder).
Up until Mojave, I'd never done a "clean install" on a Mac for performance reasons. Once doing so worked for my laptop, I followed suit on my desktop.
Did you have Adobe Creative Cloud installed by any chance? I had the same issue, and found out after several reinstalls that Adobe’s core sync finder extension was the cause.
Doing the dreaded "clean install" fixed my issues (primarily a Finder that would routinely spend up to 30 seconds or more displaying the contents of any folder).
Up until Mojave, I'd never done a "clean install" on a Mac for performance reasons. Once doing so worked for my laptop, I followed suit on my desktop.