Last month I posted some tips to help speed up Firefox.

Strangely, Firefox has been giving me some performance problems lately. It loads all the content of a page and about half of the images. Then it has an extremely long pause, maybe 2 or 3 minutes, before it finally completes loading the rest of the images.

After about an hour of uninstalling, re-installing, and tweaking, I have narrowed it down to the pipelining settings.

If I turn OFF network.http.pipelining the page and all the images load completely, but if I turn it back on, I get the same half-loading behavior.

The issue seems to be that on web sites that do not support pipelining, setting pipelining on prevents all the images from downloading.

Google is an example of a site that does not support pipelining, so if you turn pipelining on and do an image search, only about half the images will show up on the results page.

Lottery Post supports pipelining, but some of the ads, which are coming from another company's ad server, do not. The result is that most of the page loads great, but when it gets to loading the ads everything grinds to a halt.

As a result, I strongly recommend turning pipelining OFF ("false") in the Firefox web browser. Set both network.http.pipelining and network.http.proxy.pipelining to false.

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P.S. After discovering all of this I came across a Mozilla tip which contains a warning about pipelining. So disabling looks to be a very sensible idea!