Do you get out of breath quickly as well? Do you ride with others so that you can measure your performance against theirs as you may be expecting too much of yourself? I don't know your age or fitness level but it might be worth getting the once over from your GP just to make sure there is no underlying health problem causing the lactic acid build up.
What helped me most to improve on hills (when I used to be moderately fit), was to do intervals on a small circuit eg. find a small loop with a moderate to steep uphill section which takes around 30 seconds to climb, go at it as fast as you can and rest on the way back round – then go hard at it again, repeating 5 or 6 times.The 'loop' should be big enough so that you have almost fully recovered from the previous uphill sprint but not quite and you should be absolutely knackered after the last attempt. HTH