-The easiest way to run performance tests is to say "make perf-test", (or
-simply run the notmuch-perf-test script). Either command will run all
-available performance tests.
+The easiest way to run performance tests is to say "make perf-test".
+This will run all time and memory tests. Be aware that the memory
+tests are quite time consuming when run on the full corpus, and that
+depending on your interests it may be more sensible to run "make
+time-test" or "make memory-test". You can also invoke one of the
+scripts notmuch-time-test or notmuch-memory-test or run a more
+specific subset of tests by simply invoking one of the executable
+scripts in this directory, (such as ./T00-new). Each test script
+supports the following arguments
+
+--small / --medium / --large Choose corpus size.
+--debug Enable debugging. In particular don't delete
+ temporary directories.