Bladerunner has released some new MUI prefs for MorphOS 1.4.5 PowerUP Edition. As the original MorphOS 1.4.5 uses a lot of gradients, blending and other eye candy it might run very slow on the underpowered PowerUP Amiga systems. The new MUI prefs which you can find here basically disables all these things. Bladerunner also suggests to use the "Rainy Blue" skin as this might also give another speed improvement.
Please report your experiences with the new prefs in the comments section.
Bladerunner has also released a new skin called Cyberstorm (Screenshot).