C# or Java, the whole request pipeline processing should be more or less the same. Unless one platform does things less efficient than the other.

Rails and Django do things differently as to my knowledge they do it by spawning processes instead of threads. There are app-server for Rails or Django that may use threads for efficiency/performance reason but I am under the impression the whole LAMP stack is still 1 request 1 process (even though they re-use those processes from a pool of already allocated processes).