When a user selects: "Run All," if any tests have been previously run, create a new column in the table for "Test Run #i" and fill the test result figures in that column.
In situations where the "Elapsed Time" column has no value, set both columns, but in case of a conflict only fill in the "Test Run" column.
This would let someone run the test suite twice and see the difference in timing between the runs.
I'm new to the system, but it seems like some tests change markedly in time on the second run while others don't. I'm assuming there's some sort of caching done, and this feature would give feedback on how well that is working.