I cannot believe the results (below) I'm seeing on my MBP-M1 with R2019b. R2018a showed slower benchmarks as expected for Matlab running with Rosetta especially on graphics front. But strangely R2019b is zipping fast.
Results on R2019b, connected to power and no peripherals.
Out of curiosity, I connected an external monitor whose resolution is only somewhat lower than MBPs (2560x1080) and re-ran bench. Graphics seemed way faster, like running Matlab on Intel. The results are incredible.
Results on external monitor: