My last LAX arrival was on BA283 in Y the Saturday after Thanksgiving Day, I think the immigration e-gates have speeded the process up a fair bit. After stepping off the plane I would suggest a brisk walk and try and pass as many people as you can, I would have been curbside easily under 30 minutes from stepping off the plane had I not been pulled over by customs, which had to be the most painfully slow process I've ever encountered. Lots of staff milling around doing very little, only to then be grilled by the customs guy on how I could do a 17 day visit with just carry on luggage.