On scalability and memory footprint
iamelgringo: Your bottleneck in a web app is almost always the database.  In some cases, it's not.  So, it depends.If, like furiouslol, you're trying to access a 2-3 million row table and Active Record is topping out at 2GB of RAM and taking close to 1 second on a  production machine just to render a page, then yes, you might need to worry about memory usage.But, if you're prototyping a site, and just getting it off the ground, I would worry about memory usage later.If you're really freaked out about performance, you can always try PHP or Django.  They tend to be a bit more sparing on system resources.