does unbalanced tires, slow down your top speed?

[blueb8llz]

ok, im running a emaxx 3905, mmm/7xl geared 24/68 with 2x2s 5k 25/50c neu energy lipos. on
brians speed calculater, supposely i should be around the 40mph mark.
i have no rubbing in the drive train. so when im doing speed runs, my truck is ok fast, but not fast like the emaxx s ive seen on videos with the same setup or even a slower setup. is it because the videos make them look faster? i do notice my tires are somewhat unbalanced, but i have one tire that is more unbalanced than the others where when i zoom the truck by me, ill hear clump clump clump.
so will this be the cause of this? if so, how much speed does a unbalanced tire approxametly be slowing me down if any? i know this is a veeery hard question to answer but im just asking if anyone might know this.
ps. about how long of a street do you need for my setup to see the top end speed? in the videos, i see you guys run your truck so far back where you can barely see it anymore. for me, i just have the truck like 150ft away from me and zoom by...cus i think its topping out already ( i really think it tops out, i dont see it gaining any more speed)...or is thaaaat the reason why, cus its not even enough room to top out yet? sorry for the very long post.