I somehow stumbled upon this thread, and after seeing how horribly incorrect
@cadaveca 's response was just had to register. They even admitted they had no idea what they were talking about - said they didn't even click the link.
Buffer bloat is a serious issue but it has nothing to do with your desktop. It's caused by excessive delays in networking equipment, such as your home router or switch, or equipment within your ISP's network. You know everything else gets really slow/laggy (browsing, games, VoIP etc) when you are downloading at your connection's maximum speed? This slowdown is caused by buffer bloat. The internet protocol is designed to automatically adjust to the speed of your connection by detecting when data is "thrown away". This is commonly known as "packet loss".
Due to both marketing and a lack of understanding of how the internet's protocols are designed, manufacturers have spent decades trying to reduce packet loss to 0% which ironically has made the problem even worse than it was originally. Instead of allowing TCP (the standard guaranteed-delivery protocol of the internet) to discard data it is unable to handle immediately (and notifying the server that it did discard the data) our modern routers, switches and even the ISP's equipment will place the data in temporary storage known as "buffers". In a futile attempt to advertise "0% packet loss" to customers buying their products, they've broken a fundamental part of how the internet works by not allowing your computer to signal to the server "hey, I'm busy/my hands are full now, can you send that again later?". Instead of rejecting data, modern equipment will store it and wait for the PC to finish processing what was downloaded earlier before delivering it as normal. This means the server has no way to determine that the recipient is unable to keep up with the speed that your internet is capable of, and it continues to send as fast as possible.
The correct solution is to allow a small amount of packet loss to naturally occur - it is used as a signal to tell the server "hey, slow down! I have 1,000 other pieces of data to open first!", and when this brief packet loss happens, the server slows down to the correct speed (eventually). If you use a router that is configured to have low buffer bloat, you can play a game, chat on Skype and run torrents (even without setting a download speed limit!) all at the same time, and due to this automatic speed detection you won't even notice an impact. Think of it as if you were responsible for cars parking in a parking lot with one entrance and one exit. If you have a big parking lot (large buffer) and you keep allowing new cars to drive into the lot even when it's nearly full, eventually the exit will get stuck in a traffic jam due to the number of people fighting to drive out. On the other hand, if you have a small parking lot, or you start turning away new cars after the parking lot is 80% full - you've reduced the amount of people fighting over the exit, and thus increased the "throughput" of the parking lot.
So yes, I would say buffer bloat is an important metric and a problem that plagues nearly everybody using a typical home router.
As for the NIC itself,
@cadaveca is correct when it comes to home usage. The speeds available on residential connections simply aren't fast enough for you to notice a difference. If you're transferring data on your LAN however, Realtek is going to be noticeably slower than an alternative like Intel. There are several reasons why, all fairly technical, so I will spare you the details.
