Thrashing is an OS issue, not an application one. The OS should be the one
tweaking the page cache to prevent it. If the OS is not doing it by itself, one
needs to tweak their system's page cache size and configuration.
- hack extra `os.Remove()` calls to avoid leaving temporary files around;
- try using temporary directories that usually live in RAM;
- disable broken tests;
- stop printing to stdout/stderr;
- decrease test constants to make slow tests bearable*.
(*): tests are bearable in RAM (~5s) or on SSDs (~10s). HDDs are still too slow
for them (~2m).