In 6.2 on my Macbook Pro it loads okay (starts with a warning about my graphics drivers but runs anyway) and most of the gameplay is without problem. Every once in a while though, it will hang in the middle of some movement with the sound looping forever.. it seems to happen just after new stuff has loaded or cached becomes active or something. It hasn't happened in the middle of battles is the main thing. But the hangs have either required me to force quit Steam, Crossover, and wineloader (to finally kill the audio loop) - or it has frozen my whole system! I haven't determined what circumstance would be causing this.
Otherwise I'm getting good playability. The only odd slowdowns are with rocky places (like after you fight the giant antlion that butts you to death and the following combine.. that rocky pit where you enter a building for more air duct crawling) - similar to the slowness I found at the cliffside in Lost Coast.
All my Steam games still seem to be loading slowly and Episode One is no exception. But then, steam games loaded slow on my old Windows PC too.