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 milli

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.