Code using the Any type

any.swift

import Foundation

let date = Date()

var array = [Any]()

for _ in 0..<100_000 {
    array.append("Hello, world")
}

var array2 = [Any]()

for _ in 0..<100_000 {
    array2.append(array.removeLast())
}

print(Date().timeIntervalSince(date))
print(array2.count)

59ms on debug, 11ms on release both rounded to nearest the ms (rounded down)

If you replace Any with String it becomes:
28ms on debug and 4 ms both rounded to nearest the ms (up)