This quick and dirty code evaluates the code performance to convert strings with leading zeros to strings without leading zeros. 2 methods are used: double conversion String to int then int to String and regular expressions

main.dart

void main() {
   

  // Returns empty string
  String s00 = '00';
  String s0 = s00.replaceAll(new RegExp(r'^[0]*'), '');
  print("convesion of 00 with RegExp returns empty string: '$s0'");
  
  String s01 = '01';
  String s02 = '02';
  String s03 = '03';
  String s04 = '04';
  String s05 = '05';
  String s06 = '06';
  String s07 = '07';
  String s08 = '08';
  String s09 = '09';
  
 
   
  Stopwatch stopwatch = Stopwatch()..start();
  RegExp regexp = RegExp(r'^[0]*');
  for (int i = 0; i < 999999; i++) {
    String s1 = s01.replaceAll(regexp, '');  
    String s2 = s02.replaceAll(regexp, '');
    String s3 = s03.replaceAll(regexp, '');
    String s4 = s04.replaceAll(regexp, '');
    String s5 = s05.replaceAll(regexp, '');
    String s6 = s06.replaceAll(regexp, '');
    String s7 = s07.replaceAll(regexp, '');
    String s8 = s08.replaceAll(regexp, '');
    String s9 = s09.replaceAll(regexp, '');
  }
  
  print('RegExp executed in ${stopwatch.elapsed}');
  
  stopwatch = Stopwatch()..start();
  for (int i = 0; i < 999999; i++) {
    String s1 = int.parse(s01).toString();
    String s2 = int.parse(s02).toString();
    String s3 = int.parse(s03).toString();
    String s4 = int.parse(s04).toString();
    String s5 = int.parse(s05).toString();
    String s6 = int.parse(s06).toString();
    String s7 = int.parse(s07).toString();
    String s8 = int.parse(s08).toString();
    String s9 = int.parse(s09).toString();
  }
  print('Double conversion executed in ${stopwatch.elapsed}');
}