If your wanting to reduce db hits, you could setup a cron job to send all output to a variable which is then placed in either a file as mentioned before or in a table in a database. This way you will only have one db hit per page hit.
Personally, I'm hesitant to use files for a task like this these days. A well thought out database can do it much more reliably and efficiently. If you do it with files you have all sorts of issues to deal with regarding filenamming etc.
Are you using heavy resources at the moment? If not, it's probably not worth doing anything to something that already works.
Under linux you can run a phpfile under the console (this scripts and cron jobs can be made from this) by typing:
php yourfile.php>yourfile.html
This will generate your html file for you.
I would imagine that this will be the same under windows, however you will either need to set the environment var %PATH% to include the directory of the PHP binaries or specify it in you command line eg:
c:\progra~1\php\php.exe yourfile.php>yourfile.html