I see that you need more robust site. Minor modification that you asked in the bid will not resolve your problems: they will mask them for short period only. I am offering you radical solution:
1. Enhance database using all SQL 2008 R2 goodies (stored procedures, bulk operations, tables in the parameters, …)
2. Rewrite the application as modern ASP MVC application,
3. Reduce postbacks with AJAX + jQuery.
I performed such work some weeks ago for Australian employee surprising him: new application on old server with Windows XP started working at the same speed as elder version on much more power server.
I am going to finish the job in 3 weeks (21 day).