What are the performance implications of different Swift features?

Different Swift features have varying performance characteristics that affect application performance.\n\n• **Value vs Reference Types:**\n\n// Value types (faster for small data)\nstruct Point { let x, y: Double }\nlet points = Array(repeating: Point(x: 1, y: 2), count: 1000)\n\n// Reference types (better for large data)\nclass LargeData { \n let data = Array(repeating: 0, count: 10000)\n}\nlet objects = Array(repeating: LargeData(), count: 1000)\n\n\n• **Method Dispatch Performance:**\n\n// Static dispatch (fastest)\nstruct FastStruct { \n func method() {} // Static dispatch\n}\n\n// V-table dispatch (medium)\nclass RegularClass { \n func method() {} // V-table dispatch\n}\n\n// Message dispatch (slowest)\nclass ObjCClass: NSObject {\n @objc func method() {} // Message dispatch\n}\n\n\n• **Collection Performance:**\n\n// Array: O(1) access, O(n) insertion\nvar array = [1, 2, 3]\narray.append(4) // O(1) amortized\narray.insert(0, at: 0) // O(n)\n\n// Set: O(1) average lookup\nvar set: Set = [1, 2, 3]\nset.contains(2) // O(1) average\n\n// Dictionary: O(1) average access\nvar dict = ["key": "value"]\ndict["key"] // O(1) average\n\n\n• **String Performance:**\n\n// Inefficient string concatenation\nvar result = ""\nfor i in 0..<1000 {\n result += "\(i)" // O(n²) complexity\n}\n\n// Efficient string building\nvar parts: [String] = []\nfor i in 0..<1000 {\n parts.append("\(i)")\n}\nlet result = parts.joined() // O(n) complexity\n\n\n• **Memory Allocation:**\n\n// Stack allocation (fast)\nlet value = 42\nlet point = Point(x: 1, y: 2)\n\n// Heap allocation (slower)\nlet object = MyClass()\nlet array = [1, 2, 3, 4, 5]\n\n\n• **Optimization Tips:**\n• Use value types for small data\n• Prefer final classes when inheritance not needed\n• Use lazy properties for expensive computations\n• Avoid unnecessary ARC traffic\n• Profile before optimizing