When using the new AWTGLRenderer, it helps performance to set Config.glVertexArrays to true, because it reduces load on the command queue. It usually is a good idea to use this setting in OpenGL mode, but especially when using this renderer.
Funny thing about the renderer is, that jPCT gets multithreaded for free when using it. Scene management, transformations and stuff happen in one thread while the actual painting happens in another (the dispatch event thread). This is noticable on a HT/dual cpu machine: Where an application uses around 50% (i.e. one cpu) when using the GLRenderer, it starts to use up to 95% when using the AWTGLRenderer. Would be interesting to see the performance of this on a real dual cpu setup, because hyperthreading doesn't really cut it...