The single most life changing thing that I have discovered when trying to play gypsy jazz is “scale stacking”. This is when you take a small piece of arpeggio and stacking it by repeating the exact same pattern exactly one octave up and two positions higher. In general, this means you can stack 3 times.
Learn a small arpeggio pattern of any size and practice stacking it. Actually, for practice you can play ANY small 2-4 not pattern and practice stacking it and building speed.
If you want specific patterns, email me and I might share them. I am really curious who is out there that appreciates my little postings. None of the Portland people talk about theory much and neither do they seem to read my site and so I rarely get feedback, and there are a lot more ideas in my head just waiting to escape.