Having large amount of subnets (and other tables) on unoptimised MySQL database server can significantly increase page loads. To see which parameters need to be change I usually use mysqltuner perl script, which connects to database, analyses data and proposes which parameters need to be changed that are not optimally set based on current load.
mysqltuner

Installation is simple:

1.) Fetch mysqltuner on FreeBSD:

cd ~
fetch http://mysqltuner.pl

or wget on linux:

wget http://mysqltuner.pl

2.) Make it executable:

chmod +x mysqltuner.pl

3.) And run it to analyse database, you have to provide administrative credentials.

./mysqltuner.pl

Any other similar scripts out there you would recommend?

brm