Anyone who has tested more than a few graphics cards has observed that there is not always a very big performance delta between an AGP graphics card and a similarly configured PCI graphics card. The typical comeback goes something like...
"In today's games and benchmarks, AGP isn't even turned on yet. Just wait till games actually turn AGP on with big textures and stuff. Then you'll see a huge difference."
Allow me to debunk this belief by going through the typical sequence of questions and answers. Then I will get into the details behind the whole situation.
Is AGP faster than PCI?
YES, but not by much.
Is AGP faster than Local Graphics Memory?
Will an AGP2x board be faster than a 1x board?
Isn't it true that any AGP board will be faster than any PCI board?
Does graphics accelerator performance improve when AGP texturing is turned on?
No, graphics accelerators DECREASE in performance when using AGP mode.
Does AGP enhance CPU performance?
NO. When AGP texturing is used, CPU performance also DECREASES!
Then why is it that sometimes AGP cards score better than non-AGP on benchmarks?
This is usually because the non-AGP texture management software implementation of the application or benchmark in question is not very efficient. Game developers pay special attention to the performance of their texture swapping capability. The best techniques can show equal performance under normal circumstances. Some benchmarks may use a less optimized approach.
What can I do to avoid the negative performance impact of AGP?
Make sure you have a generous configuration of high performance graphics memory, and don't buy a i740 based board (unless Intel "un-breaks" its drivers).
What is AGP good for?
It is a safety net in case you weren't wise enough to buy enough graphics memory for your card. As games get more complex and require more texture memory, they will still run, but probably much slower than if you had enough graphics memory.
When that time comes, should I buy a faster CPU or more graphics memory?
Intel wants you to think that you need a faster CPU, when in fact all you may need is a few dollars worth of graphics memory. This is why Intel likes AGP so much. And this is why they crippled the i740.
How is the i740 crippled?
I'll save that for the end.