Feedback on tremolo picking motion

Hey everyone, just started out here at CTC and worked through the Primer until the end of the reverse Dart thrower tutorials. I have been struggling with fast tremolo passages in my favorite Metal songs for a long time (1-2 years). Attached you can find my attempts to play a tremolo passage for toxic garbage island from gojira. I try to do it with the reverse dart thrower motion that I just learned in this course. Usually when I speed up, my wrist wants to lift off and then I think I do more of a forearm rotation picking motion. I attached a video of that as well. Right now, Im trying to force my pisiform bone to the bridge so my wrist doesnt lift off. Starting at 180 bpm, I usually tense up very quickly. 190 / 200 are not possible for one repetition of the riff yet. I would greatly appreciate feedback on what I am doing because I acquired a lot of knowledge during the courses but struggle a bit to apply it. Cheers!