It would be minor. The British went to great lengths to ensure that the camouflage paint on their 'high speed aircraft' was consistently finished to a high standard to minimise the effect it would have on performance. The resident technical officers and inspectors in the various aircraft factories were expected to ensure that aircraft came off the line finished to the required standard. Later the RAF was continually advised and cajoled into maintaining the finish. There is a good instructional film in the Australian War Memorial collection showing how to maintain the finish on a 'high speed aircraft' (a Spitfire in this case) but I can't find the link to it.
Cheers
Steve