I missed the dev meet up, I'm on holiday in Istanbul at the moment, here's some additional thoughts i had nodding off last night:
I don't  know what the performance bottle necks in the canvas are but i had a think about vector graphics performance and this is what I identified: caching of objects and image sections, reducing the  fidelity when an object is being modified dynamically, improved drawing  algorithms (integer) ... that's a no brainier (fits in with fidelity), clipping (which also fits in with caching), and finally JIT compiling drawing operations with dynamic elements in their inner loops so that they can be properly optimized out, vectorized and unrolled etc...