I agree with qball, its normal, my Ex60 takes about 10-15 min to warm up proper and move with proper power. I usually let the machine warm for 10 min, then cycle the hydraulics for a few min before I start, my understanding is that the hydraulic oil needs to come up to temp. When its -10c I let it warm up for about 20 min just to treat it nice.
Has this always been the case with your unit and how many hours are on it?