You may find it helps to accent every 4th note - should make it easier to keep track of the notes flying by. To be honest, I don't think this is a tune that needs particularly tight tremolo picking. If you listen to the recording there are subtle changes in the rhythm.
Anyways, it's practice as always. I personally do all my practice without amplification - that way you can make damn sure it sounds good clean.... then it sounds amazing with a bit of drive :D
Agree with the other posters, except on the 4 clicks per beat idea - as the guy says, they get so close together it's very difficult to keep the beat I find....
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