game became too slow because of language callbacks

[Areso]

Make a check whether the game loaded locally or not. If loaded from a web-server then load localizations as text files. If loaded from a local drive then load localizations as js files.

if (document.location.host) {
  // remote file over http or https
} else {
  // local file
}

switch(window.location.protocol) {
   case 'http:':
   case 'https:':
     //remote file over http or https
     break;
   case 'file:':
     //local file
     break;
   default: 
     //some other protocol
}