I got Windows 10 running really fast, lean & mean, all good and dandy except for this one small issue. Whenever I browse through my folders, 99% of the time folders open really fast like they should, but then once in a while I double-click on a folder and nothing happens for about 7-10 seconds. Windows is still responsive, but not the window where some folder was double-clicked on. It can be ANY random folder anywhere on the system, not necessarily with media or even files. Could this be because I disabled indexing service and unticked "Allow files on this drive to have contents indexed in addition to file properties" on my OS drive/partition. I did the same in Windows 8.1 and I never got these hangs/freezes. They happen ONLY during folder browsing, mostly on HDD though. It feels like its a bug in Windows 10...
Do you have multiple HDDs? Could be power saving option that turns HDDs off, when you arent using them. Some of my antique HDDs that are still plugged in, are quite slow to "wake up" from sleep also (like 5 seconds or so), but I use them so rarely, that I'm keeping the power saving option on for now. With SSDs I'm not noticing any delays at all.
I have 1 SSD (2 partitions) and 1 HDD - both are SATA III using Intel RST drivers. My Power Plan is set to High Performance and "Turn off HDD" was set to 20 minutes before I made this thread. Now I set it to "Never", but I don't know whether it helped... yet.