Hi, I posted a question a year ago about Windows 8.1 gradually slows down issue, and it seems still not being solved. I recently found some new clues about this, hope it can be useful. (Please read the original post first since it contains basic descriptions of the issue: https://social.technet.microsoft.com/Forums/en-US/f9ab40a8-6681-4c66-bdbd-9de7b2fb021f/windows-81-gradually-slows-down-after-hours-speed-returns-normal-if-restart-explorerexe?forum=w8itproperf)

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This issue is found to be somehow related to total Page Faults of explorer.exe since it starts. The majority of page fault is created by desktop background slide show. On my laptop, the slide show is set to randomly switch between 53 jpegs (mostly 1920*1080) every 10 seconds. The Page Fault Delta of explorer.exe is usually 2 per second when not doing anything, and tenth to hundreds when there are some actions. But at the instance when the background is switching, it will peak to a value between 13,000 and 30,000.

I don't know if this value is normal or not, but when the total Page Faults reaches about 20,000,000, a slight slow-down can be observed by moving your mouse up and down on the favorite bar items in IE (the right bar shown when pressing Alt+C in IE), a slight lag can be observed. The slow down (slightly) of normal windows can be observed when Page Faults reaches about 40,000,000. At that time, the mouse lag on favorite bar items becomes much more obvious. After another few hours, the slow-down will become more serious.

I tried to disable the slide show by only using one background image, the total Page Fault stays low and the slow-down issue does not occur after one day (the Page Fault after one day is also far less than 20,000,000). That's why restarting explorer.exe can temporarily fix it. I tried it on 2 other Windows 8.1 computers and get the same results. Maybe there is some memory allocation or fragmentation problem building up? One thing I don't know is that if this is caused by the background slide show itself, or if explorer.exe in general will slow down after experimenting enough page faults.

• Edited by Polyhedron Zero 15 hours 19 minutes ago