Why is IE so much faster?

I've been using Firefox and Opera for the last several years, and just today I tried IE to load a page other than Microsoft Update. IE loads pages instantly, while the other browsers have noticeable and sometimes lengthy delays. This is on my old PII machine. On my newer Dell Centrino notebook, I see no difference at all. I would really like to continue using my favorite browsers, but after seeing how much faster IE is on the older machine, it will be hard to. Why is IE so much faster?

Actually, I have a PII as well, running now :)

I thought the same, except IE didn't run instantly. It just waited in the beginning a little and then showed content in a second. But then opera 9.5 alpha/beta came out. Then opera felt faster than IE by FAR.?

IN SP1 of Vista (beta currently) IE is much faster at parsing javascript and other things.

Ive fiddled with Gran Paradiso but I dont like Firefox's UI next to IE7 on Vista, and its not as secure out of the box as Gran Paradiso doesnt run in the sandboxed protected mode like IE7 does.