The “last packet successfully received from the server XXXXX milliseconds ago” errors are virtually always caused by stale connections. There are a number of possible solutions, most having to do with small code changes. Here are things to try to alleviate the issue. I apologize in advance if these have already been tried; I’m shooting ..
Below is a fairly comprehensive list of most widely used performance testing tools for measuring web application performance and load stress capacity, current as of this post date (2012-09-19). These load testing tools will ensure your application performance in peak traffic and extreme stress conditions. The list includes open source as well as licensed performance ..