OMG the ENTIRE first sentence of Firsty Lasty’s comment is SO right! There is some really solid advice on here for sweep picking. Most of which I’m taking to heart as well. As far as my personal advice goes for left-handed work on sweeps, they ARE tricky. But One of the biggest things for me is I had to learn (especially with HTTK and Nightmare) is that if you can’t play it faster, you don’t know it well enough. There are little nuances between EACH note that may make your fingers stumble. Such as is this an actual STRAIGHT 8th note sweep or are there little rhythmic aspects that make it difficult to time? Are your fingers actually pressing down accurately between each frets but not pushing TOO hard or TOO soft on the string, thus, inhibiting your sound and/or speed? When I was practicing sweeps for these two songs, I…KID…YOU…NOT, I had to slow it down to SLOWER than half speed for MONTHS. I would play it at ONE speed for literally 30 minutes straight. It enabled me to be able to detect all these little nuances. Then, if I felt I got that slow-ass speed down after 30 minutes, I’d only speed it up by ONE BPM and do it another 30 minutes. Your muscles and hands WILL approach each BPM differently, as it makes a big difference. For example, I don’t need to use my speed-picking technique at 125 with 16th notes, but the MOMENT it hits 126, I have to start utilizing it. If I jump it up to 130, I won’t know why everything locks up and gets tight and I suck and can’t do it. If you are not adept with sweeping already, it IS a difficult concept that will take MONTHS if not YEARS to achieve greatness with it. Be patient and persistent with daily practicing. Let everything “fall” into place when sweeping and don’t try to fight anything.