Someone else in here was saying they have no problem with it under Rosetta. So not sure if that is really it, I will try to get this installed on my Intel Mac over here (use PowerPC for gaming) and post something about performance back on this thread.
What I have tried that works, and usually my copy runs very well (kudos to devs for supporting OS X) is: Vertex buffering ENABLED, Texture downsampling to at least 1/2 or maybe 1/4, 800x600 on the resolution. It is possible that different system monitor color-depth and resolutions could affect how the game is drawing, so you might want to change those and check. Maybe it is actually Crystal Space having an issue with the Intel chips, rather than PS client itself?
My original comment here was probably slightly out of place. I asked how one would go about donating hardware to Atomic Blue. I am in the game a lot and enjoy both it and the community. I have posted myself elsewhere in the forum about contributions, PS actually saves me money IRL, and if one has the resources a project such as this is a write-off. I work software and it is very hard to produce and release software without proper hardware to flight it on at least, if not compile it on directly. You can do it of course, but there must be a first test, and it is better if one does not have to wait for results. Thank you.