It seems no matter what, after five to six years of working on a system, my computer performance eventually begins to drop to a crawl. When it gets to the point where junk cleanup, registry sweeps, defrag, boot optimization and virus scans are no longer helping, I will usually take a clean HDD and reinstall the current OS and then reinstall all my files and programs. This works and I am usually good for another few years. But it is a lengthy process.
Does anyone have any suggestions on a better way to do a complete spring cleaning to a computer without doing what amounts to a factory restore?
Just in case it helps, here are the specifics on the one machine that is giving me issues:
Dell Precision 5810 - x64-based PC
BIOS: Dell Inc. A09, 9/26/2015 v2.8
RAM: 32gb
1Tb HDD System Drive (Migrating to 1TB SSD)
Windows 10 - Version 10.0.17134 Build 17134

I appreciate any suggestions and welcome any questions.