I would definately go the Database route, the performance is much better.
As an example i recently put together a script which required the CSS style rules to be editable by a system admin.
What i ended up doing was storing the styles in a MySql table which had ID,StyleName,StyleRule columns. I then used a PHP called on every page access which pulled these out and delivered them to the page as a linked style sheet.
An admin page in the background then allowed these to be changed on the fly while the site was being used.
Performance was good and it happily served the 200 or so school children that where using it.
Databases are designed for this kind of high impact use, and with modern versions of MySql you can tune the server so that it keeps frequently accessed data in memory, thus making the delivery even faster.
Another example to consider is the Typo3 Content Managment System (http://www.typo3.org) thats driven entirely off a MySql DB the only thing thats static is your page template, and even then you can get away with designing your page entirely in typo script and using NO static files at all.
Cheers
Shawty