void
CxtSpeed()
PREINIT:
    LARGE_INTEGER start;
    LARGE_INTEGER end;
    int i;
PPCODE:
    QueryPerformanceCounter(&start);
    for(i=0; i < 1000000000; i++){
        no_cxt();
    }
    QueryPerformanceCounter(&end);
    printf("no cxt %I64u\n", end.QuadPart-start.QuadPart);
    QueryPerformanceCounter(&start);
    for(i=0; i < 1000000000; i++){
        cxt(aTHX);
    }
    QueryPerformanceCounter(&end);
    printf("cxt %I64u\n", end.QuadPart-start.QuadPart);
    QueryPerformanceCounter(&start);
    for(i=0; i < 1000000000; i++){
        no_cxt_no_glr();
    }
    QueryPerformanceCounter(&end);
    printf("no cxt no last error %I64u\n", end.QuadPart-start.QuadPart);