Infeasibly slow TestExecution

Some test scenarios imported from builtin-actors are infeasibly slow when executing on the fvm-workbench.

These should be identified and diagnosed. The most likely source of slowness comes from tests that iterate through epochs and require cron to run at each interval to progress the chain state.

Start by locating the test scenarios imported from builtin-actors and measuring their execution in the fvm-workbench. Compare scenarios that advance epochs and require cron at each interval, then document which cases are infeasibly slow and the suspected cause. Done means the slow scenarios are identified and diagnosed with reproducible findings.

Written by the indexing model from the issue text.