Cortex V2.03 render speed

We have noticed a significant difference in the render speed when for example transcoding from Avid MXF 1:1 to DPX between version 1.5.4-b7510 and version 2.0.3-b8235.
Using the same source clip Im able to render on version 1.5.4 at 50fps.
Version 2.03 runs at almost half the speed at 22fps.

We discovered that our DPX writer was creating fragmented files and made some changes to prevent that from happening. Can you verify the fragmentation of the DPX files from each version on your end? If for some reason you are not having issues with fragmentation, we can look at adding back the changes that made the writer faster.