I hvae Dell pricesion big problem sound crackling & system usage 100%

[Geniussajan]

I hvae Dell pricesion T 3500 with 12 GB ram, now a days i have a big problem to listen sound crackling when i use my sonyvegas audio project, the cpu usage ammediately increase till 100% & as i stop the sony vegas usage come down to 5 %, i cant work & listen sound properly please help me

 

[Kingbrutt]

is the sound coming from the computer its self , or from an audio device ?