Wings slow osx lion

Once the poly count goes above ~7000 wings really starts to slow down.  I tried earlier versions and unto 1.3.0.1 its fine (although that won't let me open the tweak menu.) Later version run like molasses. No problem under windows 7, 120,000 poly sphere was a breeze.  Why is this?  It's worse it the object has any topography changes. 12,000 poly round speaker model and the program bogged down.