I will be seeking other options for serving content to everyone else.
All that mini Ajax requests heavily depend on latency. But looking to the loading times:
GET http://www.vpsboard.com/ [HTTP/1.1 301 Moved Permanently 468ms]
GET http://vpsboard.com/ [HTTP/1.1 200 OK 2262ms]
GET http://vpsboard.com/public/min/index.php?ipbv=fde4f4cdb69df7b19270d159363cf6c6&f=public/style_css/css_6/footer.css,public/style_css/css_6/custom.css,public/style_css/css_6/ipb_help.css,public/style_css/css_6/ipb_common.css,public/style_css/css_6/ipb_styles.css,public/style_css/css_6/calendar_select.css [HTTP/1.1 200 OK 1014ms]
GET http://vpsboard.com/public/min/index.php?ipbv=fde4f4cdb69df7b19270d159363cf6c6&g=js [HTTP/1.1 200 OK 2028ms]
GET http://vpsboard.com/public/min/index.php?ipbv=fde4f4cdb69df7b19270d159363cf6c6&charset=UTF-8&f=public/js/ipb.js,cache/lang_cache/2/ipb.lang.js,public/js/ips.hovercard.js,public/js/ips.quickpm.js,public/js/ips.board.js [HTTP/1.1 200 OK 2028ms]
GET http://vpsboard.com/index.php?s=c86be6f42d683ea9b6cdc5543f17a479&app=core&module=task [HTTP/1.1 200 OK 2745ms]
You should think about merging and moving the css/js files to another box. Or at least try to serve them on static files and not through php.