It is running fine out of box on crossover 12.
First, you probably should use DirectX 9 with newer versions of Wine, unless you are using really old hardware. WineD3D runs better with DirectX 9 now. Simply turn off the features that can be costly. (Namely motion blur, bloom and HDR.)
I noticed that there are some font issues in the options menu, but not the same as there used to be. Again they are similar to the current issues in Team Fortress 2, so it is likely in the HL2 version of the source engine that is used for this game.
As of the issues with looking through the portals causing some lag. It seems to only affect certain things on me. If you see yourself through the portal it can generate large amounts of lag. This is reduced if you turn off motion blur, but is still there. Other moving objects with simpler animations seem to have fewer issues.
Other than the issue with looking at yourself through a portal, the frame rate is quite good, even on modest hardware.