I would suggest that there is no simple speed test for Moodle, or any other web application.
The subject is so complex that almost everything you read is voodoo and superstition.
To give just one example of the complexity, for years people obsessed about the speed of their servers and databases etc. in generating the HTML document, then Steve Souders measured it and showed that for most sites that accounted for only 20% of the time that the actual user spends waiting.
http://developer.yahoo.com/blogs/ydn/posts/2007/03/high_performanc/
Which is a great, a better understanding of how things work is always good, but now you don't have to just understand Linux and
MySQL and PHP, you also have to understand HTTP and Proxy behaviour and Browser Caching and the different
javascript behaviour of different versions of
IE to understand whether a change is actually an improvement or not. Oh, and have a better grasp of statistics than 90% of software developers, scientists and doctors have been shown to have. (There's a rant by an internet-famous ranty software guy, with lots of rude words in it, with the title of "Programmers Need To Learn Statistics Or I Will Kill Them All", which you can google for if you're interested)
So, if you follow the standard performance advice in setting up your server (i.e. use a PHP
Cache, use gzip) and Moodle (i.e. don't leave theme designer mode on) and measure your server to ensure you're not hitting any bottlenecks then from that point on I'd just use whatever features appeal to you. It's a massive task to prove (in all but extreme cases) that one Moodle setting is better or worse than another to a noticeable degree, so I'd spend my time elsewhere.