What I noticed is that overall, KLAX is the best performer, but it's no secret that the performance also depends on the area in which the airport lies. KFLL performs as good as KLAX, for example, even though it's a way smaller airport. However, all of southern florida, especially the Miami region, performs rather badly on my machine compared to other parts of the US. As for KDFW, it's not that great, performance-wise. It's less good than KLAX, but you say it's an even bigger airport than KLAX, so I suppose that's the reason. KJFK and KORD perform badly, but that's not so much because of KJFK and KORD themselves, rather the terrain around it. I have "pimped" NYC and Chicago to a degree that the sim isn't that happy any more, although the biggest problem seems to be UTX with all the extra roads and traffic on them. The performance drop at KJFK only started after installing UTX USA. Must say that PHNL does perform very well, also together with MegaScenery Hawaii.