How to resolve the 100% disk usage on my iMac 27" (late 2013) when in Bootcamp bootup
The solution to my particular problem is to be found here which suggests excluding the process MsMpEng.exe from the windows defender service. I'm running windows 8.1 so this done by searching for Windows Defender in your programs, clicking on the settings tab (far right) and then browsing to 'C:\Program Files\Windows Defender\MsMpEng.exe' and adding it to the excluded files and locations. Disk usage reduces drammatically!