There are some other entries that can also speed up mozilla browsers. Any number of mozilla forums carry these tips. Essentially, what you are doing is allowing throughput to stream through without excessive error checking. Every packet sent and received carries a checksum value and if the values are the same from the transmitter to the receiver, that packet is ok'd. If it fails, then it is dropped and retransmitted. That's what the pipelining is for. It just allows a continuous stream without the breaks to check the packets. Works well on clean telephone lines and broadband in general. I have found, however, if you have a good broadband service provider, I really don't see much difference.

Normally the browser will make one request to a web page at a time. When you enable pipelining it will make several at once, which really speeds up page loading.
 
nglayout.initialpaint.delay - This value is the amount of time the browser waits before it acts on information it receives.