EDIT: I do check the latest daily amgaos4 build of ScummVM on x5000 and find out that while all new games work: Sanitarium Grim Fandango Escape from the Monkey island The Longest Journey Myst3 etc some of them have some issues that happen on PPC only. For example, i report that about Myst3:
https://bugs.scummvm.org/ticket/13169
if anybody can check on morphos those games on any hardware you have and post the results that may help to improve things for all of us (or at least to know if it os4 suck some amiga1200).
I also before was disappointed by the FPS I got in Grim, Monkey, and The longest journey but it turns out that I build all with full debug and no optimization at first, and now once enable optimization and co all fast.
There s results that i had on x5000/gl4es in OpenGL mode all default:
Monkey: 75 FPS Grim: 50 FPS The Longest Journey: all fast (dunno what fps are).
if someone can bring some tests from morphos that will help much.