[Question] struggling with tremolo picking across strings and keeping rhythm. Any advice?

So I'm learning the solo to one by Metallica at the moment and the tapping bit is fine, but I'm really struggling with the short tremolo picked segment afterwards on the high e and b string where there's 3 picks per note and it swaps to the b string then back. I'm really having trouble even practicing slowly because 3 hits per note is hard to play anyway and I can't swap smoothly and I'm seriously losing faith that I'll even manage to learn this tiny segment which isn't even hard It just doesn't even sound right and ugh. This will probably get lost but no YouTube video has helped at all so far.