Hi I was wondering, what technique is used in the very beginning of just by radiohead?
because I'm learning the song...

I can hit single notes at such a high speed, however you have to strum power chords at that speed... And I feel like I need another technique to do that...

So do I? Or do I just need to practice?
Maybe it's my pick thickness too? (Which is fairly thick at 1.14 mm)

Thanks in advance
It's just strumming really. You have to focus on economy of motion, try not to hit any other strings than the ones you need to. Also I believe you're wanting to play octaves. You shouldn't need a specific pick for a specific technique. Try to find just one that works for everything more or less.