General :: Using 'find' And 'grep' In A For Loop?

I have a server hosting 100+ websites. I need to quickly identify which websites are configured with a database. There are way too many to manually check every website for a PHP file with a database name. So, I created a list of all databases from MySQL and put them in a text file. I then exported the text file to a shell variable and used it in a for loop.

bash variable

Code:
DBLIST=`cat dblist.txt`
Example of $DBLIST

Code:
db1 db_testing2 database_clientname production words4cheap
for loop

Code:
for db in $DBLIST; do find . -type "f" -iname "*.php" -exec grep -i $db '{}' ; -print; done
Note: my find statement starts searching at . which is the directory that contains all of my websites and their data, each website is setup in a sub directory, identified by it's domain name.

Example: I'm in /var/www. Beneath /var/www are a list of directories:

[URL]

However, this is taking too long (it's been running most of the day) and I was wondering if there wasn't an easier way to accomplish what I'm trying to achieve?