Let's not jump to conclusions if one of the T/R was deployed. The possibility exists that the crew deployed it after ground contact in an attempt to slow the a/c.
Several have mentioned about slow acceleration or apparent lack of power. Rananim is correct, hvy a/c, hot temps, optimum flap setting w/flex takeoff power can have completely different sense of acceleration vs. a lighter a/c taking off in cooler temps from a lower altitude.