Tomatoes and sweet peppers direct or in a pot?

So raised bed in greenhouse. I decided to plant some direct and some in pots. In the past only in pots and then plant into raised bed once a decent size. Anything I put in direct germinated but barely moved. Those I put in pots (at the same time) are at least 4 times taller. I have been taking out the ones in the bed and replacing them with the potted ones.
Why would they grow quicker in pots???