дело вкуса, имхо
http://developer.yahoo.com/performance/rules.html#js_bottom
The HTTP/1.1 specification suggests that browsers download no more than two components in parallel per hostname. If you serve your images from multiple hostnames, you can get more than two downloads to occur in parallel. While a script is downloading, however, the browser won't start any other downloads, even on different hostnames.
т.е. скрипты блокируют загрузку остального содержимого (картинок)