Optimisation de mon script news

function regex($chaine)
	{
		$chaine = nl2br($chaine);
		$chaine = stripslashes($chaine);
		
		$chaine = preg_replace('#\[b\](.+)\[/b\]#isU', '<strong>$1</strong>', $chaine);//gras
		$chaine = preg_replace('#\[i\](.+)\[/i\]#isU', '<em>$1</em>', $chaine);//italique
		$chaine = preg_replace('#\[u\](.+)\[/u\]#isU', '<u>$1</u>', $chaine);//souligné
		$chaine = preg_replace('#\[q\](.+)\[/q\]#isU', '<q>$1</q>', $chaine);//citation
		$chaine = preg_replace('#\[center\](.+)\[/center\]#isU', '<div style="text-align:center">$1</div>', $chaine);//centré
		$chaine = preg_replace('#\[color=(red|green|blue|yellow|purple|olive)\](.+)\[/color\]#isU', '<span style="color:$1">$2</span>', $chaine);//couleur
		$chaine = preg_replace('#\[url=http://(.+)\](.+)\/url\+#isU', '<a href="http://$1">$2</a>', $chaine);//lien
		$chaine = preg_replace('#\[url\]http://(.+)\/url\+#isU', '<a href="http://$1">$1</a>', $chaine);//lien
		$chaine = preg_replace('#^[a-z0-9._-]+@[a-z0-9._-]{2,}\.[a-z]{2,4}$#isU', '<a href="mailto:$0">$0</a>', $chaine);//mail
		$chaine = preg_replace('#\[img\](.+)\[/img\]#isU', '<img src="$1" alt="$1" />', $chaine);//image
return $chaine;	

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<p>
    Contenu de la news :<br />
    <textarea name="contenu" cols="50" rows="10">
    <?php echo $contenu; ?>
    </textarea><br />
    
    <input type="hidden" name="id_news" value="<?php echo $id_news; ?>" />
    <input type="submit" value="Envoyer" />
</p>
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