Optimize large set of processed data for API calls

[Volmarg]

I was trying to localize the bottleneck in my API calls. That's the one

Without that:

• Start: 17:57:40
• End: 17:59:28
• Duration: 1min 48s
• Result: not even half gets transferred and each call gets slower.... and slower... had eventually timeouts

With that:

• Start: 18:05:29
• End: 18:06:06
• Duration: 37s
• Result: done, everything works

[mogilvie]

I'll have to test this, particularly around the impact of detaching the entity postFlush. I'm thinking where the controller goes on modify the entity again and tries to flush the subsequent changes but it will have been detached.