Ah gotcha. Well one of the first things I would always try if something's slow is to open your task manager and see what's being utilized. Open a few programs that cause the usual problems and keep an eye on what you see. If any columns are at really high percentages usage -- sometimes can be disk usage -- then note that down and see if any program specifically is the cause. My first guess is you need to disable
Superfetch, as this Windows 10 default program runs fine on SSDs but definitely messes up HDD and should be disabled. May not be the issue if disk usage isn't spiking, but def recommend disabling.
Also if you aren't using an SSD, definitely first check your HDD heath status as you may be near the end of its life: S.M.A.R.T. and CrystalDiskInfo first. Your HDD may not be keeping up its old speeds, and overwriting the full drive with a fresh install could wear it out quicker. Lifespan depends up to drive but only guaranteed 3-5 years.