System Admin under unix / mySQL issue.

Dear Sirs, I'm looking for an expert under Unix system to resolve my lagging issue.. My website homepage working fine, but sometimes doesn't open well, also lagging and have bad communication between VPS's. My website is under Unix system, where i did separate the website to be working on multiple VPS's, VPS 101 is for mySQL database connection. VPS 102 for CDN/images connection only. VPS 103 for Nginx configuration / visitors request. VPS 104 for website files/PHP folders. Hence my connection now to the homepage is fine, but as i said before sometimes is taking too long time to open, hence it may need some updated software because i never update it since 12/2013. Secondly i have a serous issue in admin panel, where the main issue with the session time out once i add any news..it's take too long time to respond, where the post keep lagging till the page be killed. Please make sure you can do this and fix my issue, otherwise you are wasting your time and my time... only expert and serous freelancer bidding here. Thanks all for your time!