Cobra turbo alternate picking or just high quality fast alternate picking What I refer to with this crazy name "that I got from the movie Cobra, when Stallone is in he's car pressing a turbo button and he's car drives about one percent faster" is to the concept of reaching your top speed and then with force getting just a few percent speed more.
The problem with that, with those very few extra percent you lower the quality of the sound quite a bit, with pop outs and  losing the stamina. So instead when you play fast alternate picking try avoiding using any force at all and notice how much longer you can play fast and even better you don't even really hear the difference in the tempo