unit tests take too long

[zooko]

The best way to fix this would be to optimize the code under test so that it passes the tests faster.

The second best way would be to optimize the tests so that they test the same thing but faster.

The third best way would be to reduce the "replications, redundancy, random stabs in the dark" and so forth, and the tests of scaling. (This cries out for another category of test that reports on scaling behavior...)

The fourth best way would be to judiciously prune tests which have been superceded by more comprehensive tests and are now redundant.