So don't for get about downloading Mobile Passport, which you can submit your customs form fast via your phone. There's a special lane for you and it helps bypass one step.

Also, LAX baggage hasn't been bad especially with Delta. They seem to come out fast since Delta has a 20 minute baggage guarantee (for domestic flights technically).

Recheck your bags after you pass customs at TBIT (or T2 if you happen to come out there). The main TBIT security is usually really really long and the secret security entrance is down by the connecting gates. HOWEVER, I would just walk over to T3 (or T2) since it's right next door and avoids a bus and usually those lines are short for security.