being a mobile processor and listed as a BGA socket, you can't upgrade that CPU.
Also, every i7 cpu is quad core with hyperthreading. If it shows up in task manager performance with less than 8 graphs for cpu usage, you probably have a driver issue holding things back. You have a £200 + cpu in there already.
oops, just looked intel ark. its a twin. They love to break there own rules. 4 threads. laptop; 30 watts; getting the gist? is what it is. maxed.