Electrical Wiring Problems?

Here's the scenario. We have been in our home about 4 months. Newly built. It has gfci circuits throughout the home. The issue I have is in at least three of the rooms, when the television, vacuum, or iron is turned on the lights dim for like a half second or so. I can handle when the ac/heat kicks on it draws more power/amps but an iron?

We had and electrical contractor for the builder come out. He said its normal, nothing he can do? What gives? Do they need a bigger breaker, etc? I had the power company come check outside, (of course theres no problem there.) Any input would be greatly appreciated. thanks a million.

d in TX