If the goal is total production per tomato plant, I say start your tomato seeds indoors in mid-January. Plants only get rootbound if their pots are too small. I've potted up seedlings as many as three times, up to 4-gallon pots or even 5-gallon buckets (with drainage holes, of course), then transplanted 3-4' tall "seedlings" in Late May and ended up with good-sized ripe tomatoes by mid-June on plants that go on to become enormous and produce 100+ lbs. per plant by the time of first Fall frost.
Two factors to make this happen:
1. Plenty of intense, indoor lighting (or a greenhouse if you've got the $) and warmth; 400W metal halide lights have worked well.
2. Soil temperature must be warm enough (at least 60°F preferred, even warmer for peppers) or the new transplants will not thrive. I think soil temperature is much more important than air temperature at getting the plants off to a fast start (no freezing temperatures, of course). Plastic mulch, or even better, a hoop house or such, can really help get transplants off to a quick start.
I've seen transplants put inside a high tunnel grow three times as fast and produce ripe fruit three weeks earlier than paired plants put in the open field. Likewise, good production continues well into November in a high tunnel, while it to comes to a grinding halt by mid-October in the open field. Physiologically, tomatoes (and peppers) are sub-tropical plants and really don't like to get their feet cold.
Agreed that trying to transplant into the open ground around the last average Spring frost date will get you little if any advantage over waiting for 2-4 weeks until the soil warms up.
If I were only planting 50 tomato vines or so, and had the $ for the extra potting mix and electricity (or a greenhouse), all my tomato plants would be started by February 1st and be in 4-gallon pots by now, growing like crazy, then be full of blossoms by a Memorial Day target transplant date.
Those are BIG if's!
And there are important goals other than total production which each grower considers before placing that first seed in soil.
Here's a picture of seedlings taken on March 27th when it was just a backyard garden:
