I have tomatoes in a greenhouse and also some planted outside. All
planted/potted on at the same time.
Those outside have very thick stems - as thick as a little finger -
those in the greenhouse much thinner and much taller. All have
reasonable quantity of flowers on.

Too late for this year - but is it worth "slowing down" those in the
greenhouse in the future - or does it not matter - if so how?

I guess I can make effort to weigh all fruits off one of each and
compare - but I'd still be interested in views/comments.