My laptop OS is Win 10. When I run Auslogics Disk Defrag, it spends the vast majority of its run time scanning files in subfolders under C:\Windows\SoftwareDistribution\Download\. . . A check of the files blows ones mind. I didn't count the files, but my guess is that there are easily 10,000, maybe more. A lot of them are listed as "manifest" files. And they're apparently compressed (right-clicking does NOT give you the usual "Properties" or "Delete", only "Extract" or "Copy"). I have never seen anything like this in earlier versions of Windows. What are they? Can I delete them (the newest of them are at least a month old)?

The reason I'm asking is because the laptop, which originally came with Win 7, is EXTREMELY slow with Win 10. . . so I'm looking for ways to enhance its performance.

I'd allow Windows 10's built in defrag to handle it.

SoftwareDistribution is where your Windows Updates are downloaded to.

Best tips I can give you right now, off the top of my head...

• Start > Type "Disk Cleanup" > Right click and Run as Administrator > then clean up everything found there.
  You can remove the old Windows install/upgrades (including the bi-annual updates/Spring/Fall/April)
• Set it and forget it. Let Windows built in defrag do it's thing. It works wonders, even on a SSD.
• Don't run CCleaner. In fact, uninstall it. It does more harm than good.

If none of those help, honestly I'd reinstall. I opted in to the upgrade, then formatted and reinstalled after I did the upgrade. The clean install worked very well. Though this was years ago. Also, I'm running on an SSD which makes a lot of it super fast.