Exactly the same happening to me! I wasn't even aware of that issue, but when I read this post, I checked the task manager and found my processor working at 20-30%. I removed the Sd card, rebooted and then it worked at 0-1%. If I add the Sd card again, nothing weird happens, but if I completely power off the computer for 15s and then start it up with the SD inserted, it idles again at 20-30%.
There are two processes making the processor work: one called System (it uses 15% of the processor) and another one called System Interruptions (using about 8% of the processor)
Another hell of an issue to add to my issues list... though this one seems to have a simple solution: just don’t use the Sd card on a 1000€ device...
Absurd to have to avoid using an mSD card in the slot designed for it! But I find it IS possible.
After cold boot and CPU at >20%, just put the SP2 in sleep state, then wake it up. Check Task Manager. CPU will be around 0%.
Try it and tell us what you find out.