For more things to upgrade, an output-cache would be fun too.
This lets the data-link speed be low, both as input & output, and more importantly it allows the sorting to be slow, so it's possible to see what happens (I would prefer to be able to lower the sort-speed even lower than lvl-1, or preferably be able to manually change the speed to whatever speeds are unlocked.)
(it would also be fun to be able to switch algorithms manually too, between those that are unlocked.)