Skipping so bad, I can't play

I launch the game and right away the sound is skipping and repeating, all the background actions is very slow, almost like it is running in the single digit frames per second. Even the menus themselves are extremely sluggish.

I tried lowering all the audio and graphics settings but no help.

Windows 7 ultimate (x64)
AMD Phenom II X4 (quadcore)
nVidia GeForce GTX 460
12GB RAM

I’m running the monitor through my HDMI cable, not sure if that has any bearing on it at all

I attemepted to minimize and “Set Affinity” to just one core but that didnt help either.

I have the same issue and tried the same steps. My specs are:

Windows 7 Ultimate (x64)
Intel i7 x920 (quadcore, hyperthreaded to look like 8)
Nvidia Quadro FX 880M
10GB RAM

I have a friend who reported the same issue to me as well. He has:
Windows 7 Ultimate (x64)
Phenom 2 Black
GTX560Ti
8GB RAM

It makes the game unplayable.

Well I restarted my computer with DVI.
Same result
Restarted again with HDMI, works like a charm, wtf

I also noticed that it wasnt just this mod, all Source engine games were doing it.
I let every game I had update and restarted and now its fine so I don’t know, must be Valve’s fault

In your case it’s more likely to be sound driver’s fault.

I’m assuming that you have your audio transmitted over HDMI to the monitor? Or at least you most probably have NVIDIA High Definition Audio devices installed in numbers if you check for them in Windows device manager. If you happen to have any of HDMI audio outputs enabled among output audio devices in windows control panel there could be sound-related problems in case your monitor can’t process the audiostream which gets transmitted on HDMI interface and fails to ACK/NACK packets propely. Then you could get stalls while audio driver waits for the monitor to answer until it times out. Rinse, repeat, say hello to the resulting stutter.

Founded in 2004, Leakfree.org became one of the first online communities dedicated to Valve’s Source engine development. It is more famously known for the formation of Black Mesa: Source under the 'Leakfree Modification Team' handle in September 2004.