I’ve had similar issues with sites like this. Here’s how I solved it.
First, I put everything aside.
Next, I asked myself what I wanted. Did I want the ease of dynamic content, and all that came with it, or did it matter if I had to chop up a ton of files, and in the end have straight static content?
Next, I looked at how often the content was updated. My answer was frequently.
I decided that I really needed the dynamic content, and features only it can provide.
So, that left the next part. The sites in question in each case were taxing the host. Problem: The site had outgrown the host.
Finally the decision. Static contant with the current host, or find one that could support the load.
I decided in each case to get a better host. It didn’t come for $5, but the additional cost paid for itself. If you’ve really got the traffic to warrant looking at this (dynamic vs static), most likely you can offset the additional expense in some form or fashion.
Summary: Figure out what you want in your site, then go from there. If it means changing hosts, and even getting a dedicated box, go for it.