jak przyśpieszyć ładowanie str_replace()

Witam

 
echo'<a class="panel_login_text"><i>Miasto:</i></a>';
echo'&nbsp;<select id="loader" name="stan" style="border:1px solid black;" required onclick="city1()">';
echo'<option></option>';
foreach(glob('db/*') as $folder){
	if(is_dir($folder)){
		include("voivodeship.php"); //ładuje województwa
			echo'<optgroup label="'.$voivodeship.'">';
			foreach(new DirectoryIterator($folder) as $filecity){
				if(!$filecity->isDot()){
					$path=$folder.'/'.$filecity->getFilename();
					$city=basename($path);
                                                include("city.php"); // na ładowaniu zamiany mi sie muli
					$city=str_replace(".php","",$city);
					if($city!="index"){
						echo '<option value="'.$path.'">'.$city.'</option>';
					}
				}
			}
			echo'</optgroup>';
	}
}
echo'</select><br>';

plik city.php

 
$city=str_replace("ABahA","Augustów",$city);
$city=str_replace("AwJFt","Białystok",$city);
$city=str_replace("CdwlC","Bielsk Podlaski",$city);
$city=str_replace("DbxSQ","Brańsk",$city);
$city=str_replace("DPofO","Choroszcz",$city);
$city=str_replace("esjkv","Ciechanowiec",$city);
$city=str_replace("FdfOW","Czarna Białostocka",$city);
$city=str_replace("fDMLH","Dąbrowa Białostocka",$city);
$city=str_replace("fNKoS","Drohiczyn",$city);
$city=str_replace("GBvrV","Goniądz",$city);
$city=str_replace("gWoIQ","Grajewo",$city);
$city=str_replace("hLyeb","Hajnówka",$city);
$city=str_replace("idHOK","Jedwabne",$city);
$city=str_replace("IehAm","Kleszczele",$city);
$city=str_replace("inRNY","Knyszyn",$city);
$city=str_replace("JbEBD","Kolno",$city);
$city=str_replace("kghLI","Lipsk",$city);
$city=str_replace("kJFtk","Łapy",$city);
$city=str_replace("KjmQY","Łomża",$city);
$city=str_replace("lFAIg","Mońki",$city);
$city=str_replace("lFowN","Nowogród",$city);
$city=str_replace("meiEm","Rajgród",$city);
$city=str_replace("nBvCE","Sejny",$city);
$city=str_replace("nclFq","Siemiatycze",$city);
$city=str_replace("PAZNY","Sokółka",$city);
$city=str_replace("pgPdB","Stawiski",$city);
$city=str_replace("QMdmv","Suchowola",$city);
$city=str_replace("QMqpg","Supraśl",$city);
$city=str_replace("qyNYU","Suraż",$city);
$city=str_replace("rxyDP","Suwałki",$city);
$city=str_replace("SeCAy","Szczuczyn",$city);
$city=str_replace("USXYL","Tykocin",$city);
$city=str_replace("VfvrV","Wasilków",$city);
$city=str_replace("VRgKE","Wysokie Mazowieckie",$city);
$city=str_replace("yTMLp","Zabłudów",$city);
$city=str_replace("zAyui","Zambrów",$city);	

i mój problem polega na tym że nie wiem jak przyspieszyć zamiane nazwy pliku na miejscowość bo przy większej liczbie miast skrypt się ładuje przez dłuższą chwile

Dzięki wszystkich z góry za pomoc

dobra z braku czasu na dumanie zrobiłem preloader :-)

pozdrawiam :D