An interesting observation:
if two oops which we need to swap: oop1 and oop2 taking exactly same space in memory, then all we need to do is to swap their memory contents, instead of scanning heap and updating pointers!
This makes a become operation extremely cheap for such pairs! As for objects of different sizes, we could still use slow algorithm.
But knowing that if two objects with same size will be swapped much faster, a developers could adapt their algorithms to exploit this feature (use fixed-size objects instead of variable-sized ones etc).
Magma using proxies, which then #becomeForward: to real objects when reified. This is very costly operation and main reason why it so slow on loading objects from server. To speed thing up, a special trick can be used: - each time server sends an object ID (instead of real object) it could also send its size in bytes (or even more clever - you can encode object size in its ID ;) ). Then a client will create a proxy for given object and will try to match the size, if its possible. (nobody said that proxy can't be variable-sized, right?)
Then once client requesting to reify given proxy with real object from database, VM will just overwrite a proxy's memory contents with real object.