D compile time algorithms implementation

[khurshid]

I just have read from github  std.variant, std.typetuple, etc. 
source codes.
And I have a question.
Why more linear algorithms implemented with O(N^2) ?
example: staticMap,  it doesnot compiled  more 500 arguments.
although, following version compiled for more than 32768 
arguments:

template staticMap2(alias F, T...)
{
         static if (T.length == 0)
         {
                 alias TypeTuple!() staticMap2;

         }
         else static if (T.length == 1)
         {
                 alias TypeTuple!(F!(T[0])) staticMap2;
         }
         else
         {
                 alias TypeTuple!( staticMap2!(F, T[0..$/2]), 
staticMap2!(F,
T[$/2..$]))  staticMap2;
         }
}