OK. I tend to start Safari in the morning and open a tab for my email (Google hosted on my own domain). Throughout the day, I open and close other tabs and Safari windows but it's not uncommon to go very logn stretches without closing Safari outright. Lately I've noticed that Safari seems to be eating up a lot more memory than reporting in Activity Monitor. Today, Safari claimed to be using a few hundred MB. But I was completely out of Free Memory (down to 14 MB) without much else going on. I close Safari and BAM. 2.4 GB free. I had walked away from the computer and Time Machine had started a backup. The machine was unusable for ten minutes while I force quit safari and listened all the page in/out going on. I thought my HDD was going to explode. My usage of safari hasn't changed much in the last six months but this problem seems worse over the last few weeks. Any suggestions?