Performance issues

[paescebu]

Description

Hey @davdroman !
I have some report on CustomKeyboardKit that there are some performance implications on my library if used with an extensive amount of TextFields. (See: paescebu/CustomKeyboardKit#19)
After some digging I realized that this comes probably from the overhead that is necessary to make introspection even possible. So I doubt that this can be really improved but I'm giving it a shot to ask if there are some ideas laying around.

In short, the performance on this..

import SwiftUI
import SwiftUIIntrospect
import UIKit


struct ContentView: View {
  @State private var showSheet = false
  
  var body: some View {
    VStack {
      Button("Show Keyboard Sheet") {
        showSheet.toggle()
      }
      .sheet(isPresented: $showSheet) {
          KeyboardView()
      }
    }
  }
}

struct KeyboardView: View {
    @State private var strings = [
        "1", "2", "3", "4", "5", "6", "7", "8", "9", "10",
        "11", "12", "13", "14", "15", "16", "17", "18", "19", "20",
        "21", "22", "23", "24", "25", "26", "27", "28", "29", "30",
        "31", "32", "33", "34", "35", "36", "37", "38", "39", "40",
        "41", "42", "43", "44", "45", "46", "47", "48", "49", "50",
        "51", "52", "53", "54", "55", "56", "57", "58", "59", "60",
        "61", "62", "63", "64", "65", "66", "67", "68", "69", "70",
        "71", "72", "73", "74", "75", "76", "77", "78", "79", "80",
        "81", "82", "83", "84", "85", "86", "87", "88", "89", "90",
        "91", "92", "93", "94", "95", "96", "97", "98", "99", "100",
        "101", "102", "103", "104", "105", "106", "107", "108", "109", "110",
        "111", "112", "113", "114", "115", "116", "117", "118", "119", "120",
        "121", "122", "123", "124", "125", "126", "127", "128", "129", "130",
        "131", "132", "133", "134", "135", "136", "137", "138", "139", "140",
        "141", "142", "143", "144", "145", "146", "147", "148", "149", "150",
        "151", "152", "153", "154", "155", "156", "157", "158", "159", "160",
        "161", "162", "163", "164", "165", "166", "167", "168", "169", "170",
        "171", "172", "173", "174", "175", "176", "177", "178", "179", "180",
        "181", "182", "183", "184", "185", "186", "187", "188", "189", "190",
        "191", "192", "193", "194", "195", "196", "197", "198", "199", "200"
    ]
  
  var body: some View {
    ScrollView {
      ForEach($strings, id: \.self) { $val in
        TextField("", text: $val)
          .introspect(.textField, on: .iOS(.v17)) { textField in
              //do nothing
          }
          .padding()
          .background {
            RoundedRectangle(cornerRadius: 8)
              .fill(.gray)
          }
      }
    }
    .contentMargins(.all, 16)
  }
}

...is much worse than this:

import SwiftUI
import SwiftUIIntrospect
import UIKit


struct ContentView: View {
  @State private var showSheet = false
  
  var body: some View {
    VStack {
      Button("Show Keyboard Sheet") {
        showSheet.toggle()
      }
      .sheet(isPresented: $showSheet) {
          KeyboardView()
      }
    }
  }
}

struct KeyboardView: View {
    @State private var strings = [
        "1", "2", "3", "4", "5", "6", "7", "8", "9", "10",
        "11", "12", "13", "14", "15", "16", "17", "18", "19", "20",
        "21", "22", "23", "24", "25", "26", "27", "28", "29", "30",
        "31", "32", "33", "34", "35", "36", "37", "38", "39", "40",
        "41", "42", "43", "44", "45", "46", "47", "48", "49", "50",
        "51", "52", "53", "54", "55", "56", "57", "58", "59", "60",
        "61", "62", "63", "64", "65", "66", "67", "68", "69", "70",
        "71", "72", "73", "74", "75", "76", "77", "78", "79", "80",
        "81", "82", "83", "84", "85", "86", "87", "88", "89", "90",
        "91", "92", "93", "94", "95", "96", "97", "98", "99", "100",
        "101", "102", "103", "104", "105", "106", "107", "108", "109", "110",
        "111", "112", "113", "114", "115", "116", "117", "118", "119", "120",
        "121", "122", "123", "124", "125", "126", "127", "128", "129", "130",
        "131", "132", "133", "134", "135", "136", "137", "138", "139", "140",
        "141", "142", "143", "144", "145", "146", "147", "148", "149", "150",
        "151", "152", "153", "154", "155", "156", "157", "158", "159", "160",
        "161", "162", "163", "164", "165", "166", "167", "168", "169", "170",
        "171", "172", "173", "174", "175", "176", "177", "178", "179", "180",
        "181", "182", "183", "184", "185", "186", "187", "188", "189", "190",
        "191", "192", "193", "194", "195", "196", "197", "198", "199", "200"
    ]
  
  var body: some View {
    ScrollView {
      ForEach($strings, id: \.self) { $val in
        TextField("", text: $val)
          .padding()
          .background {
            RoundedRectangle(cornerRadius: 8)
              .fill(.gray)
          }
      }
    }
    .contentMargins(.all, 16)
  }
}

Or do you have any idea how this can be worked around without using the introspection capability?