I would try to update your video driver and check the your monitor and video settings. try a lower resolution and refresh rate.
hkcmd.exe is installed alongside Intel multimedia devices and allows configuration and diagnostic options for these devices.
If you open Task Manager and kill hkcmd, does it kick back off automatically and does explorer usage lower?
You may try to kill the explorer process as well in task manager and then choose File>NewTask and type explorer.exe to relaunch it. See if it continues to eat up cpu usage.