it's bound to be quicker than using SSI for includes

Apache mod_include SSI is seriously underrated.

If you need speed mod_include is faster than mod_perl and mod_php.

If you need more power simply integrate mod_include with mod_perl for Perl Server-Side Includes.

From Apache Hello World Benchmarks:

1. Hits/sec - Web Application Software
2. 4285.2 --- C Apache API mod_hello
3. 3557.5 --- HTML static
4. 2475.5 --- mod_include SSI
5. 2128.7 --- mod_perl handler
6. 1601.2 --- mod_php PHP