Gunkan, the J2M5 is as fast as P47 and p51 at alts above 6000m(or so).
Compared to late war American and German fighters, the Jak-3 is too slow and too limited to low and medium alts, starts to lose engine power quickly after 4000m. J2M to high alts only... Personally I find the VK107 powered Jak-9U much better, ahead of La-7, but still behind P51, P47 and late FW190s.