There are many processes. I want to know if you can kill the feature with a group policy setting or something. EDIT: I found some settings on gpedit.msc but they are useless.
Open task scheduler then select: Microsoft>Windows>TaskScheduler and disable "Regular Maintenance" & "Idle Maintenance"
There is not need to do that if you have SSD in windows 8 because it will not defragment(optimize) SSD drive...
Locate maintenanceui.dll in C:\windows\system32, take ownership of it and rename it to maintenanceui.dll.bak.