The online immigration app someone mentioned upthread I think might be US Mobile Passport Control. You can use that even if you don't have Global Entry, which is what I did before we got GE. But I am not sure if they always share a faster-moving line - MPC might sometimes have its own line. I know I filled out the MPC online the first time we came through after getting Global Entry and the agent said there was no need to do that -- it's one or the other, and with GE you don't have to fill out any immigration form to get back into the US.
I haven't had to fill out a US customs form in some time. We travel light and don't bring souvenirs to or from so we're always in the "nothing to declare" line. Some other countries still do the customs form, although many have an online process. We just got back from Roatan, Honduras and they have an online customs declaration that you fill out both on the way into the country (or up to 5 days prior to entry) AND upon departure, too. The agent just scans a QR code on your phone. Other travelers didn't anticipate needing the form and it held up the line a bit because they did not have paper forms available, just the website on the phone.
Side note - there've been a couple of times where I've almost run out of pages with my passport so I've always been very cognizant of the entry requirements for other countries. They often specify how many blank pages you need to enter their country as well as how much time you must have left before your passport expires (usually 6 months at least). On our flight back from Roatan, a flight attendant escorted a young woman to the row behind us and had a chat with her. She had apparently arrived to Roatan on a direct flight from Miami, only to be turned away by Honduran immigration because she only had 2 months validity left on her passport rather than 6 months. She was irate because the airline had looked at her passport twice before boarding in Miami and no one said anything about the expiration date. THEN, not only was she denied entry into Honduras but she was put on the very next plane back to the US -- which was heading to Dallas, not Miami. So it was a good reminder to me to make sure to always check the requirements of our destination country. I often enroll my trips with the State Dept's STEP program, too, as the consulate will have a way to contact you if they need to send out info prior to departing or while you are in the destination country.
The facial recognition in the DFW GE area was so nice -- did not even need to take my passport out, just breezed through almost without stopping!