Might you be complaining about this gentleman? http://ask.slashdot.org/story/13/01/03/2255204/ask-slashdot-how-to-react-to-coworker-who-says-my-code-is-bad
I wish I had mod points for this.
Compared to PHP, Java is much faster when it comes to business logic. A combination of PHP for user-facing material and Java for business logic and database interactivity is the best of both worlds solution.
Facebook uses HipHop (http://en.wikipedia.org/wiki/HipHop_for_PHP) to convert PHP to C++ to gain some speed advantages. Also, they use a database back-end called HBase (http://hbase.apache.org/) which is written in Java.
Your 1200 users are not the hundreds of thousands the poster is looking at/for. For this, I recommend Java with Cassandra or HBase in the back end. Cassandra (http://cassandra.apache.org/) and HBase are both NoSQL and are limited only by disk space availability. Postgres/MySQL/*SQL can also be used when relational information is mandatory. At work we did some research and found that for large data sets, NoSQL write speeds were an order of magnitude faster than Postgres/*SQL. Those writes included encrypting the data before writing to the database. Read speeds were on par with each other.