Audio and video distorted intermittently while doing a webcast in IE

A lot of this is going to have to do with how your stream is configured and how the video player is written.  The technology provider for your multicast solution (TalkPoint?) is in the best position to troubleshoot that.  I'm also not able to get to your stream from here, but it's kind of moot.

If your stream and video player are configured to take advantage of hardware video decoding in Flash Player, your CPU load should be in single-digits when playing the stream back (all of the decoding work is offloaded to the GPU).  If you're decoding in software (that could be the result of failing to encode the stream in a hardware-accelerated format, or in not taking advantage of the hardware-accelerated StageVideo APIs available in ActionScript), that could definitely not perform well.  The software decoding path is heavily optimized, but there's only so much you can do on that front.  There's a reason that GPUs exist, and that hardware-accelerated video is widely used.

Either way, the conferencing technology vendor knows their code, and is in the best position to help you tune their product for optimal performance in your environment.  We make a profiling tool called Adobe Scout, which is available for free, and should point them to any hotspots in their code.

It's also worth thinking about what your transition strategy off of Flash is going to be.  Upcoming browser changes are going to make it increasingly difficult to use this particular solution in your environment.  You might be better served by finding a replacement vs. trying to solve for this particular problem.

Flash & The Future of Interactive Content | Adobe Blog