An interesting problem of the P-38 was that its aerodynamic performance was severely degraded in cold skies due to higher air density which in part accounts for its much poorer performance in ETO than PTO or MTO.

The P-38 was a monster in PTO. The hotter, thinner air made much of its compressibility and maneuverability problems go away. It was much faster than the Zero, had superb range and outgunned everything the Japanese had. In the excellent Fire in the Sky one Japanese naval intelligence officer rued that the appearance of the P-38 meant the Empire irrevocably lost the war in the air. Lindberg in an authorized combat patrol flew the P-38 and shot down a zero--all he had to do, he wrote, was to turn into the Japanese and flew head to head to the zero because with the firepower of one cannon and four HMGs he would be victorious by default.

In MTO & PTO it was initially a match for the early Bf-109 and Fw-190 models. Once the 109 G and 190 D models enter production, not so much.