Tikky, at the altitudes required to engage Heavy Bombers in the ETO/MTO, the P-47s held significant performance advantages over the Luftwaffe fighters.
The P-47s typically didn't reach their best speed until 32,000 ft. Up there, they out-climbed, out-turned and easily out-ran the 190A and 109G-6 subtypes they generally encountered. Even later German fighters, such as the 190D-9 and 109G-10 fell short in performance up that high. Even after the P-51 appeared, it still lacked the high alt performance of the Jugs, especially the late model Jugs (P-47M and in the PTO, the P-47N). Mustangs performed better at medium altitudes (15k to 25k). Down here the Jugs were not nearly as effective and the 109s and 190s could and often did give them a very difficult time.
P-47s owned the thin, cold skies over Europe. And why not? It was designed and engineered specifically for that environment.
I read where one Luftwaffe pilot stated that no matter how high they climbed in their 109s, they always found P-47s higher. Some P-47s groups flew high cover up as high as 37,000 feet!! I'm not sure a combat loaded 190A could even get that high and 109s were surely out of breath (and horsepower).
My regards,
Widewing