How much do you weight? The more you weight the less shaving a few ounces off your bike makes sense.

As far as performance goes, buy easy to maintain equipment as you do not have a team to keep it in shape for you. I would suggest an internally geared hub even though a derailer is mechanically more efficient if maintained properly.

You might be better of spending the money getting more sleep and better conditioning as the bike is really not the most important factor in performance.