I explicitly stated in my post that I was unsure if he was using a php framework. I try to avoid unfounded assumptions, although I certainly make them.
Scaling can be overemphasized: it doesn't matter if it scales well if it doesn't work. Beyond that, Rails and Django both have sites getting hit with huge quantities of requests. Beyond that, many of the issues with scaling are database issues, not framework issues. As such you will have those same database issues regardless of the framework you chose.
I see scaling well on a Django site as being simpler than scaling well on php. Django has a potent caching system that is easy to activate (the creators of Django also created memcached, so the integration is exceptionally well done, but you can also cache to files, a database, etc), and it can be configured to cache at the level of granularity required (specific db queries, entire pages, components of pages, only for users who are not logged it, etc).
I have no doubt there are reasons to be using php over rails or django, but I don't think that scaling is one of them.
Finally, writing your own framework is the antithesis of doing something that scales well: your company and your programmers also have to scale along with your software.
The issue with Rails for me wasn't the database bottleneck. It was the ActiveRecord. It was using far too much memory and was taking up the bulk of the page loading time. After i migrated the app to my php framework, I downgraded to from a 2GBz 1GB RAM server to a 2GHz 512MB RAM server and i still get a performance boost. Running the rails app on the 512MB server was painfully slow.
Writing your own framework is a good compromise if it can give you that performance boost that the other frameworks can't give you. I've tried the other PHP frameworks and the best page loading time i got was 0.9s.
Scaling can be overemphasized: it doesn't matter if it scales well if it doesn't work. Beyond that, Rails and Django both have sites getting hit with huge quantities of requests. Beyond that, many of the issues with scaling are database issues, not framework issues. As such you will have those same database issues regardless of the framework you chose.
I see scaling well on a Django site as being simpler than scaling well on php. Django has a potent caching system that is easy to activate (the creators of Django also created memcached, so the integration is exceptionally well done, but you can also cache to files, a database, etc), and it can be configured to cache at the level of granularity required (specific db queries, entire pages, components of pages, only for users who are not logged it, etc).
I have no doubt there are reasons to be using php over rails or django, but I don't think that scaling is one of them.
Finally, writing your own framework is the antithesis of doing something that scales well: your company and your programmers also have to scale along with your software.