I suggest following changes in Vertex template:
index.php, line 36
<link rel="stylesheet" type="text/css" href="http://fonts.googleapis.com/css?family=<?php echo $s5_fonts_highlight ?> />
to
<link rel="stylesheet" type="text/css" href="http://fonts.googleapis.com/css?family=<?php echo $s5_fonts_highlight ?>&subset=cyrillic,latin" />
and
/vertex/css_and_js.php, line 28
<link rel="stylesheet" type="text/css" href="http://fonts.googleapis.com/css?family=<?php echo $s5_fonts;?> />
to
<link rel="stylesheet" type="text/css" href="http://fonts.googleapis.com/css?family=<?php echo $s5_fonts;?>&subset=cyrillic,latin" />
Thanks!