My solution as well, my ethernet card is buggy, sometimes one works and not the other or visa versa.No one else in the house can stand to wait the extra 10-30 seconds Firefox takes to load compared to IE.
This was fixed about eight months ago. Firefox now loads in about five seconds or so.
I run both and see no discernable difference in loading times. How fast is FF, I load 4 tabs as my home page, Google, FreeRepublic, Broadband Reports and The Weather Channel and they just pop-up, no delay, on a 5Mbps cable connection. Today because of the storm The Weather Channel was slow but that was everywhere.
My son did have problems with FF loading and we traced it to his Panda antivirus , some pages would only load halfway or not at all and some were sluggish, enabling pipelining with the Tweak Network Settings extension helped some but the true solution proved to be changing AV's.