After update 10.5.20 my CPU is VERY HIGH!

Try disabling your cpu’s virtual cores through your BIOS, and try it again.

I note steinberg doesn’t like to be forthcoming with this suggestion, but will suggest a myriad of other potential sources, first, for these issues. Many users are simply unable to use hyperthreading in this version without those cpu (ASIO internal processing) overloads, and this is documented.