Jeremy> I've made some simple measurements of how long opcodes take to Jeremy> execute and how long it takes to go around the mainloop ... Jeremy> Comments and questions are welcome. I've got a little time to Jeremy> do more measurement and analysis before devday. Interesting results. I've been working on my {TRACK,UNTRACK}_GLOBAL opcode implementations. I have an optimizer filter that sets up tracking for all LOAD_GLOBAL,{LOAD_ATTR}* combinations. It's still not quite working and will only be a proof of concept by devday if I do get it working, but I expect most of these expensive opcode combinations to collapse into a LOAD_FAST, with the addition of a TRACK_GLOBAL/UNTRACK_GLOBAL pair executed at function start and end, respectively. Skip