IE6 clients download spacer.gif from wrong URL many times

If Confluence is set up without a context path, there will be a performance impact from requests being served for spacer.gif. This is a particularly large problem when the clients using Confluence are Internet Explorer 6.

The primary problem is that the requests use the wrong URL and hit the (slightly expensive) 404 page:

"GET /display/CONFEXT/undefined/images/border/spacer.gif HTTP/1.1" 404 40448 196468

That's 40 KB download in a response that took 196 ms to generate. By contrast, a 200 response for this file serves 43 bytes in 2 ms and also gets caching headers returned so subsequent requests get a 304 response.

"GET /images/border/spacer.gif HTTP/1.1" 200 43 1632

The other related problem is that IE6 clients request this resource once per comment on a page, rather than once for the whole page.