ImageEngine/cortex — pull request #359 by johnhaddon (2014-11-25 11:08:19+00:00)
Title: Optimised Object::memoryUsage()

- Reduced number of set lookups by performing find/insert in one
- Removed bookkeeping for objects with only one owner - they should never be counted twice anyway

This knocks 20% off the total runtime of a certain Gaffer benchmark.