Whenever I Securely Empty Trash, my Macbook starts working really hard. The CPU stays over 80%, Fans start cranking up, case starts heating up, pinwheels start turning, dogs and cats start raining down... ok maybe not the last part. What is happening? I thought typically securely emptying the trash would mean the HD is being written over several times but I did not think it should put such a load on the CPU. Any insights? I mean it is running as hard as it does when encoding/decoding video.