     
     func testPerformanceWhenSomeChange() {
         
-        let quarter = 1000
+        let quarter = 10000
         let items = (1...(4*quarter)).map{ Item("\($0)") }
         let firstPart = Array(items[0..<3*quarter])
         let secondPart = Array(items[quarter..<4*quarter])

    
    func testPerformanceWhenEverythingChanges() {
        
        let half = 1000
        let items = (1...(2*half)).map{ Item("\($0)") }
        let firstPart = Array(items[0..<half])
        let secondPart = Array(items[half..<2*half])

    
    func testPerformanceWhenNoChange() {
        
        let items = (1...40000).map{ Item("\($0)") }
        
        self.measure {
            let diff = Diff.calculateFrom(previous: items, next: items)
