Skype Technical Frequently Asked Questions: "Why does Skype seem to use all of my CPU?

Skype might start using 100% of CPU if you have TotalRecorder software installed and it is set as default Input/Output device for Skype. To avoid this change the I/O devices to your soundcard or USB Phone in the Skype options menu or change the default Windows I/O device from the Windows Control Panel to your soundcard or USB Phone. In most of the similar cases it has turned out that the reason is incompatibility with some other software components installed on the computer (for example: antivirus Nod32, network monitoring software like Netlimiter).
Also, be sure to turn off Windows XP speech recognition feature. The speech recognition engine kicks in when you begin a call and can cause your CPU to run at 100%. Turn off the speech recognition by opening the Control Panel and selecting Regional and Language Options. On the Languages tab, under Text services and input languages, click Details. Under Installed services, click Voice Recognition under the language you are using, and then click Remove.

If you don’t have these programs and your PC has enough resources, please let us know about it by using the problem report form."