Python is an interpreted language, similar to Java in concept. Python.exe is the interpreter that runs python scripts. It of itself is mostly harmless, BUT if yah have gotten a rogue or badly written script launched on your machine, it can hog cycles like no tomorrow!!!
To test this, remove python from your startup and see if anything yah want the machine to do is broken. If yah know for certain that yah are running python scripts, take each one down and see if that eliminates the CPU drain. If yah are not running python scripts, then suspect that a rogue script has gotten onto your system.