Hi Guys,
I stumbled across this in a thread unrelated to Crossover games / Wine. If you place the d3d9.dll from falloutnexus into the Rift Game folder it will make a massive improvement to the FPS in rift.
For ATI
http://www.newvegasnexus.com/downloads/file.php?id=34970
For Nvidia
http://www.newvegasnexus.com/downloads/file.php?id=34778
Place in /Users/<name>/Library/Application Support/Crossover Games/Bottles/RIFT/drive_c/Program Files/RIFT game/
I went from about 8fps in sanctum to ~27 fps on my ATI 5770, using the normal renderer on Min settings.
Just need a fix for the tearing models now.