As @Teunis noted, increasing the ASIO buffer size can reduce CPU load quite a bit. If you're recording voice or an instrument, it's helpful if you can run cleanly with a buffer of 256. If mixing, a buffer of 2048 usually works very well. Any buffer size greater than 256 will give you noticeable latency.
If you're having trouble recording glitch-free, try to kill as many unnecessary tasks as possible. The less you ask of your PC, the better.