I get high (40-50%) CPU use when I run the Arduino IDE on Windows 10, as a portable installation. It's noticeable as it causes the fans on my laptop to spin up and stay on continuously, which is unusual.
I can start the IDE without the problem occurring, and CPU usage doesn't go up until I switch to a different window and back again. You can see the contrast in the screenshot here.
On the process list, almost all usage is down to 'Java(TM) Platform SE binary (32 bit)'.
I tried turning off antivirus protection as other threads have suggested, but no luck.
Thank you for the reply, apologies for the slow response.
I've since gained some more understanding of the problem - clicking away from the Arduino window and back again seems to cause it to enter its state of high CPU use. From here, scrolling, typing, or compiling code makes no difference and CPU use stays high. But clicking on a menu or changing tab makes the CPU use drop back down to normal levels.
The antivirus doesn't seem to be the problem since a) the antivirus process is not what's taking CPU time, and b) CPU use rises and falls based on actions within the Arduino IDE.