The run in the Vivaldi arrangement

… works best if I hold my right arm in a somewhat hollow, gawky, ungainly fashion almost as if it’s not part of me.  Align the knuckles so that they are not parallel to the keyboard but so that the index finger knuckle is a bit further away from the keys.  Keep the palm hollow and lifted, and the side of the ribs taut.  Disconnect from the arm.  Hold your elbow a bit out from your body.

Always always always focus intent on the top note of the chords, and play them over and over to settle the voicing and synchronize them.  Do not rush this process.  You will suck at first.  Go slow, and do the dried peas trick.