Performance does not scale well for several parallel tasks

[wagoodman]

This takes several seconds to run:

config:
#  log-path: build.log
  max-parallel-commands: 12
  event-driven: false
tasks:
  - name: Processing
    parallel-tasks:
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test
    - cmd: echo test