Too tight chains will soak up power like you wouldn't believe. When I was a kid I had a 25 hp motor cycle and if the chain was too tight it couldn't go past 50mph. It would do 80 with the chain set right. On the motorcyle the check was to have the chain so that you could easily deflect it by an inch with your finger in the middle of the top run. Not sure how to set it up on a bicycle. It would certainly be less than that. It shouldn't be tight though.

+1 on the wheel alignment issue. You get horrible wear and chain failure if that is wrong.