Gem parallel_tests runtime-log records incorrect times

I have an enterprise installation using the parallel_tests gem - everything almost works save for the runtime output. I get runtime logs for each and every spec, but some are logged with extremely long runtimes.

Locally
./…controller_spec.rb:27.283746 # Long, but stay with me

On CI
./…/controller_spec.rb:261.822707796 # Impossible!

There are a dozen examples of tests taking an order of magnitude longer on CI compared to their runtime locally, but after collecting them, and comparing their implementation and ordering, I see no correlations. In addition, the build timing tab in the UI for a given container states 11min of runtime, but when adding up the runtime logs for each spec, I get in upwards of 15min for that same node.

I’ve removed guard, omitted logging for ‘rspec retry’, and restricted tests that are run to certain directories, all to no effect, and still I see the same distribution of extreme runtimes.

Has anyone seen this behavior? Any tips/ideas?