Is going faster the key to a higher GRE score?

No. Going faster usually means making more careless errors, which costs you more points than the extra questions are worth. The key is working at an efficient but controlled pace on the questions you're actually solving, and spending closer to zero time on the ones you're not.

Think of it this way: if you rush through 27 questions and get 20 right, that's worse than carefully solving 24 and getting 22 right. You want to do all of your work at a pace where you actually get credit for the questions you know how to answer, rather than losing them to careless mistakes driven by rushing to reach questions you're likely to struggle with anyway.

The real time savings come from skipping strategically, not from solving faster. A question you guess on in two seconds frees up two full minutes you can spend being careful on a question you're likely to get right.