F# inline and effects on performance

gistfile1.txt

open System
open System.Collections.Generic 

[<Struct>]
type Pair<'a  when 'a: equality> =
    val v: 'a
    val w: 'a
    new(x,y)= {v=x;w=y}


let pair x y = new Pair<int>(x,y)

let  inline  Eq_cmp<'a when 'a: equality> = {  
    new IEqualityComparer<Pair<'a>> with  
        member x.Equals(a, b) = 
            (a.v = b.v) && (a.w = b.w)
        member x.GetHashCode(y) = 
          let mutable h = 17 in
          h <- y.v.GetHashCode()+(h*23);
          h <- y.w.GetHashCode()+(h*23);
          h
  }  


let perf_run i =
    let c = Eq_cmp<int> in
    let map = new Dictionary<_ , _>(10000000,c)
    for j=0 to i do
        map.Add((pair j (j*23^^^i)), i)