So there are 3 variables in running a vastly popular website:
1) Bandwidth
2) SQL server performance
3) Scripting performance
Bandwidth is the easiest to solve. You just pay more money and you get more bandwidth. But on a site as popular as WinCustomize, the number of people on at the same time (think thousands) require a lot of SQL and page generation resources.
So even as we increase the bandwidth, you then end up where the SQL server gets maxed. So then you increase your SQL server resources and then more people are able to get on until the scripting resources are maxed. That's where we are now.
You can optimize things, tweak things, etc. And you're always battling out having a site that looks nice and presents information and isn't too hard to code and maintain with the demands of thousands of users browsing the libraries at the same time.
So what got this going in the first place? First, as some long time users know, late last Fall we increased our servers and bandwidith and everything else and our traffic increased dramatically. By March, we'd reached a new level of website popularity (Which is good except that since we're not ad driven, it's a mixed blessing). But we also just launched GalCiv.com which is seeing traffic that is an order of magnitude beyond what we had projected.
We have the bandwidth situation reasonably okay, but the SQL and scripting resources are what we have to work on further.