'... I bet smaller memory use and snappiness correlate ...' one way to probably look at this is as follows: optimising on memory usage f.e. by packing/encoding

'... I bet smaller memory use and snappiness correlate ...' one way to probably look at this is as follows: optimising on memory usage f.e. by packing/encoding more information in a limited space, results in reduction of running time of programs. this is because, you reduce the amount of 'stuff' that needs to be moved around in memory (and programs are always doing that).