message: optimize `util.driveLetterToLower()` (11x faster)
diff: @@ -584,10 +584,16 @@ export class Util {
  * @param fullPath
  */
  public driveLetterToLower(fullPath: string) {
  - let match = /^([a-z]):[\\/]/i.exec(fullPath);
  - if (match) {
  - let driveText = match[1];
  - fullPath = driveText.toLowerCase() + fullPath.substring(1);
  + if (fullPath) {
  + let firstCharCode = fullPath.charCodeAt(0);
  + if (
  + //is upper case A-Z
  + firstCharCode >= 65 && firstCharCode <= 90 &&
  + //next char is colon
  + fullPath[1] === ':'
  + ) {
  + fullPath = fullPath[0].toLowerCase() + fullPath.substring(1);
  + }
  }
  return fullPath;
  }
  