Below is from a well respected web site "Gizmo"s Freeware". Perhaps it can be used to once and for all find out where the bottle necks are
The Best Web Site Monitoring Tool I've Seen
Updated 22. September 2012 - 1:12 by rob.schifreen
As someone who looks after various websites, I always like to use automated monitoring tools to check that the sites are behaving themselves. To help in this, there are various web-based systems around, many of which are free, which will automatically attempt to connect to a site every few minutes and produce a report as to whether they were able to do so and, if so, how long it took.
One of my recent discoveries in the web monitoring area is a system called Copper Egg. Accounts cost from $9 a month, but the basic service is free. The basic service lets you monitor up to 10 websites, which should be plenty for most people. Simply set up a probe by entering the address of the web page, then log into your dashboard on a regular basis to see the results of the connection attempts.
Copper Egg is capable of attempting to connect to your website from a number of different locations, and you can specify one (or all) when you create the entry. And you don't need to own the web site you're monitoring, so it's also ideal if you want to check on a friend's site. Or even that of your employer.
In addition to checking out websites, Copper Egg can also keep an eye on servers. For this, you'll need to download and install a utility on the server. The utility is available free, for Windows, Mac and Linux servers. And the free account lets you monitor up to 2 servers, in addition to 10 web sites.
If you want to keep an eye on the web, check out www.copperegg.com.