How to optimize database access?

I’ve just ported my 13 year old static HTML site into WordPress, and realized that my ambitious integration ideas led to some very slow page response. You can see it at

https://www.freebiking.org

I’ve optimized the graphics (reduced the overall size by 60%), optimized the layout, but the main problem I have (at least judging by tests like tools.pingdom.com) is the database access part – the very generation of the page from dynamic content. Therefore, I installed WP Super Cache to make life easier for some visitors, but the real solution would be if I could speed up the dynamic page generation process somehow.

I realise that I may have been too ambitious in designing the front page before all – I wanted it to include all relevant info from two of my sites, so there are several RSS feeds included. All in all, it’s not drawing data from one, but from at least 5 databases (two WordPress databases + one bbPress instalation using the same database with WordPress, one phpBB3 database, and one Gallery 2.31 database). When you add the adsense code and weather widgets, it’s a huge amount of data to aggragate. So the real question is: is it at all possible to speed up the page generation without sacrificing a part of that functionality?

Forget about paying for a dedicated server and transfering all my sites to it, I am not ready for that kind of investment.

How would any of you optimize the site in my situation? Is there a way to measure the timing of individual database access tasks in the page generation process? tools.pingdom.com gives only the page generation process as a whole, and then gives the load time of various external objects, it does not let me see which operation took how much time in the very page generation process (the first line).