I have noticed an issue since upgrading to 17.1 where the CPU usage escalates to 100% when the Kodi window is not in focus any more. More accurately, if some part of the Kodi window is visible it idles at around 12%-15% CPU but as soon as the Kodi window is entirely obscured it jumps straight up to 100%. This happens both in windowed mode and in fullscreen mode (ie, by switching to another desktop). The power draw increases and fans come on at full speed, sucking the life out of my battery.
I did not have this problem with 16.1, which could sit idle in the background all day doing nothing.
Paging @xayide and @FernetMenta who seem to be familiar with previous reports of high CPU usage.