Safari 4 running slow? - Possible fix...

1. Close down Safari (copy these instructions somewhere first)
2. Open Finder
3. Open up the Library folder in your home area
4. Then go to Caches → com.apple.Safari → Webpage Previews
5. Select all the files in there and delete them.
6. Restart Safari

Safari appears to suffer from an inibility to clear up the cache of Top Sites images, which are quite large (about 1MB per page for me, currently 350MB in total after a few days of surfing). These are not cleaned up if you use the normal “Empty Cache” menu item, a significant oversight when you consider that these images contain snapshots of many (all?) of the websites you may have visited. When there are many of them, Safari seems to slow down considerably, especially when you create a new tab or switch to the Top Sites view.

Hopefully this will all be sorted when the next version of Safari comes out.