Matrix light intensity (LUX) vs. GPIO Slowdown

[Laulund]

Hi I have been working on getting two outdoor 64x64 matrix modules to behave nicly in FPP 6.3

They runs smoothly via an E80 Colorlight board and blast out around 20.000 lux in my very unscientific measuring setup.

Unfortunately I can only get an old colorlight firmware (v11.09) to to work with FPP, newer versions of the colorlight firmware like v13.11 don't seam to work with FPP ?? - and the matrix modules need a newer version to function properly.

Instead I connected them to a Adafruit RGB Matrix Bonnet for Raspberry Pi (PI4), It works! and on GPIO Slowdown 1 it almost match the Colorlight light intensity (19.000), but flickering/glitching was everywhere.. Turing the GPIO Slowdown to 5, make it more stable but at the cost of a light intensity now below 10.000 ;(

The difference is very visible to the human eye, also on the image attached you can spot the lower refresh rate. 

I hope someone got an idea how to get some more light intensity into the matrix moduels without the stroboscopic disco effect, other hardware suggestions are also very welcome