You must be very careful comparing speeds between aircraft,particularly different types and drawing such broad conclusions. There are many,many factors involved.
I am reminded of a story told by Murry White who worked as Ernie Mansbridge's assistant on the Supewrmarine Spitfire. The prototype K 5054 had only managed a disappointing 335 mph flown by Quill on 27th March 1936. Supermarine decided to fit their own propeller,with modified tips. At 1800 hours Quill took of for another series of tests. It was White who calculated the new true air speed,his calculation checked by Mansbridge. This time K 5054 managed 349.5 mph, very close to Mitchell's estimate.
That's nearly 15 mph simply by changing the propeller.
White's reaction also gives an idea of how fast this was at the time.
"I went to Ernie and told him that I had made a mistake,but couldn't see where. He looked through my figures and said that I hadn't made a mistake,and that my figures were exactly right,and was what they expected. I said I thought it would have been more like 250 mph,but he said that if it had been it wouldn't have been very good,350 mph was what they were aiming for."
Cheers
Steve