The US Air Force has published a study of aircraft camouflage from World War II to the present day. It's titled "Olive Drab, Haze Blue and Jet Black: the Problem of Aircraft Camouflage prior and to and during WWII".
In an introductory article, Brian Duddy sets the scene.
Throughout the war, there was a continual debate over the overall value of camouflage finishes versus leaving the aircraft in natural metal or unpainted, which offered a bit more extra speed due to either polishing of the surfaces or reduction in weight. There is a speed penalty imposed by rough painted surfaces that increases aircraft drag contrasted against smooth polished metal.
Within the USAAF, there was never a consensus about which property was more important— concealment or speed - so instead they settled the issue by directing that manufacturers cease camouflaging most combat aircraft as of 1943. This instruction applied to most combat aircraft, except some tactical fleets, such as transports or gliders. In light of the progress of Allied forces it also made sense operationally – air superiority over the battlefield was now changing over from Axis to Allied air forces; German progress in radar surveillance and detection made visual concealment less vital, especially in the case of large fleets of hundreds of strategic bombers daily hitting the Third Reich. Additionally, Allied bases in the U.K. and on The Continent were less threatened by surprise air attack because of our own radar coverage. The AAF summarized the situation in April 1943, “Due to the early warning and vectoring capabilities of radar, camouflage is losing its importance when weighed against the cost in speed and weight.” Some local commanders in the Pacific still felt camouflage was necessary for use in some geographic areas.
Reducing the aircraft weight and increasing performance was now offered a better tactical advantage to fighters and bombers. The piston-driven fighter aircraft particularly needed all the speed they could get to deal with the threat from the German jets. There was also the secondary benefit of reduced cost and production time, which facilitated quicker replacement of lost airframes.
Ironically, in spite of all the years of studies and experimentation, at the end of the conflict in 1945, camouflage finishes had almost entirely disappeared from USAAF and then USAF aircraft through the 1950s. By then, radar detection had almost totally eclipsed visual means. Camouflage finishes only made a significant reappearance after operations in Southeast Asia in the 1960s brought back the need to conceal aircraft against the jungle terrain in that particular theater.