I noticed that after cold boot my HDD would constantly do something for about 5 minutes, during that time system would be mostly unresponsive. Using Process Monitor, I discovered that proccess C:\Windows\System32\CompatTel\WicaInventory.exe is doing tons of reads, and my AV (CIS) would try to scan them, so system became largely unresponcive for abot 5 minutes or so.
Searching the net, I discovered that, this process is part of a Windows update KB2952664 with somewhat vague description… Something about helping with upgrade to Win 8.
Since I couldn’t uninstall the update (I used disk cleaner to get rid of old updates’ data) I somply deleted c:\Windows\System32\CompatTel\WicaInventory.exe (using IoBit Unlocker), and now I don’t get this disk activity at cold boot.
So if you’re experiencing same slowdowns, either uninstall update, or delete the process.