I think you will need to find out which terminals you arrive and depart from. I have arrived internationally at Tom Bradley terminal and have departed internationally from Terminal 3, Tom Bradley and Terminal 4 (with Qantas and VAustralia).
I have arrived at Tom Bradley on an international flight and then had to take a domestic flight at Terminal 4. It was quite easy as the terminals were right beside each other and as our luggage was ticketed right the way through from Australia, once we collected our bags and got through customs there was a recheck area to just drop our bags as they were tagged right the way through. We then just walked to Terminal 4 as it was right beside our arrival terminal.
If Delta and Air France are partner airlines, then you will be able to check your bags right the way through to your international destination from your original domestic airline. This makes it really easy to change terminals as you get off your domestic flight with Delta, don't have to worry about your luggage and you just head over to the other terminal. There are shuttles that run between the terminals but you have a lot of time, you could just take a stroll and walk between terminals. Just depends on which terminals you are arriving and departing from and also wether Delta and Air France are partner airlines and checking your bags right the way through.
At LAX, we have always cleared customs at Tom Bradley terminal. It has been very easy and didn't take long at all but that depends on what time you arrive I guess. We are always early in the morning and it is as customs is opening. But I have always found it to be very efficent, then again if it did take a while I may not have noticed as we were so excited about arriving on our vacation in the USA