Comment 3 for bug 1738769

I used a simple sampler profile to check performance benefit. Flamegraphs were attached. You can search by instantiate_spec, example http://www.brendangregg.com/blog/2015-08-11/flame-graph-search.html
In addition, I executed a simple test. I started a 10 workflow with 40 sleep(0.01 seconds) tasks which start one after another. (1 mistarl engine)
Before fix: 29 seconds.
After fix: 16 seconds.