It's not trigger creep. it's pe travel. It's a long pull "safe action" style gun.
Yes, you can get a trigger job that takes out the pretravel, but I wouldn't do it for anything other than a competition gun or one of the SKUs with a thumb safety.
In a stock M&P, trigger pull has basically 3 phases.. pretravel, pretravel with the firing pin safety plunger engaged, and pulling through the sear. On most M&Ps, the sear doesn't have too much creep, but they are all worse than a properly prepped sear that has been polished. It can also be aggravated by a poorly finished face on the striker leg. Out of 4 strikers i have, three came badly prepped and had some machining marks in the face, and made even a decent trigger job feel creepy towards the end.
As for fast double taps (why double tap when you can practice and get a sight picture for every shot just as fast), riding the reset is fastest, but you can get 99% of the way there simply avoiding slapping the trigger. When I switched form shooting a 1911 in USPSA to shooting an M&P, I had to learn to stop slapping the trigger (not for speed, but because on a heavy 1911 with a light 3lb trigger, it didn't disrupt my sight picture nearly as badly as on a light polymer gun wtih a 6lb trigger, and even it's now 3.5lb trigger). Even when slapping the trigger, splits in the .2x range were qutie doable as long as they were under 10 yards and i didn't need a good sight picture to get As.