IE7 recently received a minor but welcome update this week, with a patch improving the speed of the built-in phishing filter. If you haven't used IE7 yet, it's filter is similar to other browsers filters in that it will scan a page to look for common fraud attempts, but was known to make a PC fairly slow when it attempted to scan multiple pages at once. Now that IE supports tabbed browsing, that's much more likely to occur. This update addresses that issue, though it still relies on the underlying principle of checking a server-side list of known bad sites.
This patch isn't pushed to your PC, and instead must be downloaded from Microsof'ts site. If you are using IE7 there's no reason not to get it!