User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10_5_8; en-US) AppleWebKit/533.4 (KHTML, like Gecko) Chrome/5.0.375.70 Safari/533.4 Build Identifier: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5; en-US; rv:1.9.0.8) Gecko/2009032608 Firefox/3.0.8 GTB7.1 While an item is being retrieved, any other tabs/windows/frames/etc... that try to access it block on read access to the cache; and so they can't render the item until it's fully received. This might be an issue with prefetch: imagine something contains a LINK rel=prefetch to a resource that's a bit slow to load. If the user clicks on the link, they won't get any rendering of that page until the resource is fully done loading. This could make prefetching, even ignoring network contention, slower than not prefetching. I'm a chromium developer, and I wrote a reproduction (attached as a python app, runs as a webserver on port 8080), and I found I could also reproduce this issue in Firefox. Reproducible: Always Steps to Reproduce: 1. Run attached webserver 2. Drive to http://localhost:8080/ 3. Actual Results: Watch a beautiful song appear in two frames. The song will, if the bug exists, show up entirely on the left, then appear all at once on the right. Expected Results: If this bug is fixed, the song should show up at the same time in both. see attached webserver.py

Gavin, thanks for the bug report!