Open Radar

 
Summary:
The isSubsetOf Set method performance has decreased dramatically in Xcode7-beta5 in comparison ti Xcode6.4 

Xcode 6.4:        0.00000046 sec
Xcode 7-beta5:    5.96 sec  

Steps to Reproduce:
- make 2 random Set<Int>
-call set.isSubsetOf(otherSet) 
- measure speed with CACurrentMediaTime

Code: 

func makeRandomSet(count: Int) -> Set<Int> {
  
  var set = Set<Int>(minimumCapacity: count)
  for _ in 0...count  {
    set.insert(Int(arc4random()))
  }
  return set
}

func measure(_ title: String? = nil, times: Int = 20, call: () -> Void) {
  var results = [CFTimeInterval]()
  for _ in 1...times {
    let startTime = CACurrentMediaTime()
    call()
    let endTime = CACurrentMediaTime()
    let time =  endTime - startTime
    results.append(time)
  }
  
  title.map { print("\($0) : ", appendNewline: false) }
  let avarage = results.reduce(0, combine: +) / Double(times)
  print("() Average - \(avarage)")
}

func test () {
  let set = makeRandomSet(5_000_000)
  let otherSet = makeRandomSet(set.count)
  
  var res: Bool = false
  
  measure("IsSubsetOf") {
    res = set.isSubsetOf(otherSet)
  }
  print(res)
}

Expected Results:
The performance should be at least the same as in old Xcode and Swift version or better.

Actual Results:
It get worse. Much worse!!!

Notes:
Test project is attached