You may be interested to know the built in Windows defrag tool since Vista only defrags fragments smaller than 64mb by default.
Worked on several machines recently, and noted that the built-in defrag works fine for machines that are used for browsing, editing docs, etc. For those involving heavy file use and movement (e.g., editing video files, moving large number of pictures around, installing and uninstalling programs), the default settings don't work well. Third-party programs plus optimizers speed them up. SSDs are very helpful but they're expensive, so additional drives are needed to run other programs.
That is similar my conclusions for the Win7 defrag back in 2013, glad to see it still holds true today.
I perform Windows Updates, then cleanup, then defrag, so about once every 2 weeks using Windows defrag at boot for maximum effectiveness. Code: Boot Windows USB - Repair - Troubleshoot - CMD - type/enter (system partition may not always be C, perform analyze to verify) c: cd windows cd system32 defrag c: /u
I just found out that there might be something (perhaps third-party programs) that does not make the system idle such that the scheduled defrag won't run. This together with particular drivers in installed software might cause a slowdown.