In the filter field, type: network.http In the field of 'Preference Name' double click network.http.pipelining to set it to 'true'. Next, double-click network.http.pipelining.maxrequests In the 'Enter integer value' dialog box, enter a higher number than the default 4. I entered 100 here.
Now, double click network.http.proxy.pipelining to set it to 'true'. Right click anywhere on the page and select New-> Integer For the "Preference Name" in the "New Integer Value" dialog box, enter the following text string: nglayout.initialpaint.delay and click on "OK"