Arri Raw Slow in AE

The more recent ARRI RAW (mxf) is painfully slow to read in AE. The previous one (EXR sequence) was slow to work with but not this slow just to read.  This leads to very long renders with only 2 cpu cores peaking ocassionally to 100% in small intervals. HDD where the media is located is at 7% max.  Both AME and AE queue have the same  performance.  Most of my compositons are very simple but are around 4k 16bit.

I use a proxy workflow but for the final render I'm stuck with long render times. None of my hardware seems to be bottlenecking so what is the solution here. This happens in both my workstations:

Ryzen 3700x

GTX 980 

64GB RAM

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Ryzen 9500x

RTX 2060

128GB RAM

Appreciate the help!