If it's an 08, then that means it's a 4-speed automatic. Yeah, it's not going to win any races, but that should have been obvious immediately. The tested acceleration number is something like 9.5 seconds 0-60, which is certainly plodding along. Later models with the 6-speed are more than half a second faster just because of how the extra gear ratios allow the engine to stay in it's power band. Even if you were able to get a full cold air intake and exhaust (worth maybe 10 horsepower) without throwing codes, you probably wouldn't feel noticeable difference in acceleration.
Even a 1.4T Cruze is faster than that, maybe it's time for a trade-in?