I have often seen the fastest and strongest rider in the group was the person on the heaviest bike. Weight means something when you are accelerating or going up hills but otherwise, it is not that big a deal.

I have seen plenty of people who put down big bucks on really high end bikes to discover that the high end bike did not make them any faster. Shoot, I had a friend who got a pricier bike and I swear he slowed down (we used to discuss this when he was not around so other people noticed it too).

Now I have noticed geometry changes affect things. I went from a touring bike to a rigid short wheel base racing bike and it made a noticeable difference on cornering and seemingly acceleration. It might have just handled better which meant I was going through corners faster. But if you are on a bike whose handling you really like, you will probably see a performance advantage.

A friend of mine looked at a ultra high end bike that was leaning against a wall and sniffed saying "Without a rider, that is the fastest that bike is going today".