It's been well-known for decades that each additional 50g on a shoe requires 1% more aerobic function for the same speed, and the gains do not magically level off as you imply.
I have heard numbers broadly in line with this but I don't have the reference to hand. I think it was a single trial rather than a meta analysis of several.
I know I feel faster with racing flats on than with trainers.
It's been well-known for decades that each additional 50g on a shoe requires 1% more aerobic function for the same speed, and the gains do not magically level off as you imply.