the P-61 (~35,000 lbs) was heavier than the A-20 (~20,000 lbs) and it could out turn P-51s, P-47s & P-38s.
from
http://www.edwards.af.mil/history/docs_html/aircraft/a-20.html:"Light, fast, and powerful, the A-20 was a good airplane. It was modern for its day, with a tricycle landing gear which allowed quicker takeoffs and gave it better handling characteristics on the ground. Unlike most twin engine bombers, the A-20 needed no co-pilot; a single pilot occupied the narrow cockpit, supported by a single gunner back aft, and sometimes a navigator in the nose compartment. Its twin Wright R-2600-23 engines drove the Havoc to a maximum speed of some 340 mph, leading some of its pilots to claim that the nimble plane was almost a heavy fighter."
unloaded, i dont see anything too weird about an A-20 out-turning a dora, after all the the FW-190s were known for their high speed handling, no? not for their ability in low speed turning fights...