//Fast version for http://www.fssnip.net/sB
//Check on 1000000 elements array

let FastSlice chunk arr=
  let len=arr|>Array.length
  let res=Array.init (len/chunk) (fun x->arr.[(x*chunk)..((x+1)*chunk-1)])
  len%chunk|>function
     |0->res
     |x->[|arr.[len-x..]|]|>Array.append res