Performance of OpenFL vs. Flixel+OpenFL

I ran both OpenFL's BunnyMark and Flixel's FlxBunnyMark on the same machine, adding bunnies until the fps dropped under 60. Windows-HXCPP-release. For FlxBunnymark, the options were: No Collisions/No shaders/Step: Variable/On-Screen. I also disabled the angularVelocity because the bunnies in the OpenFL version are not rotating.

27k bunnies for Flixel+OpenFL (at 52fps) vs. 240k bunnies for OpenFL (at 54fps).

Please forgive me if there is something obvious that I'm missing: both benchmarks are "official", I'm using the default configuration for each project, so I'm guessing they are doing the best they can to show the correct numbers. OpenFL's BunnyMark is using drawQuads, too.

Using the Visual Studio profiler there seems to be no discernible bottlenecks (as in: there are no obvious inefficiencies in Flixel that are eating the cpu time), just, the end result is that it's taking a lot more time to render.

Is Flixel unwittingly creating more work than it should for the rendering pipeline? Or is OpenFL missing some optimizations that overwhelmingly affect Flixel?

I know that there is more than raw performance to appreciate, but still: it's the same rendering engine, the numbers shouldn't be so different.

How can we approach the issue to gather more data, maybe find the root cause? Does anyone have any pointers?

Run OpenFL's BunnyMark and Flixel's FlxBunnyMark with the stated Windows-HXCPP-release settings, including the collision, shader, step, and angularVelocity differences. Use the Visual Studio profiler to compare rendering work and determine the root cause of the performance gap; done means identifying a reproducible explanation and a concrete optimization target.