Mental Ray vs maya software

As ive looked at before somethign strange is happening when i try to redner in mental ray with multiple objects. This is a screencap of my maya screen followed by the render usign mental ray.

 The screen cap of Maya, both the base mesh, and the extra objects with all map applied.







The render using mental ray.

The render using maya software. Althought the object both render, the displacement map, doesn't really work with maya software. The other problem is it takes abotu 13.25 times longer. this render took 1 mintue 46 seconds. the mental ray render took 8 seconds!