I have a feeling that hiring al3x is one of the few reasons that Twitter didn't collapse into a heap of cetacean corpses.
Twitter's original codebase started as a "my first blog" tutorial in Rails — the polar opposite of a messaging platform. That's a hell of a ship to turn around, especially live on the world stage while the userbase and datastore are growing exponentially and you're rapidly approaching the second half of the chessboard.
Facebook both very intentionally limited their growth (new colleges) and avoided their most expensive features (like photos) for as long as possible. Flickr was originally an open-ended MMO/MUD based on user-contributed content called Game NeverEnding, which was far harder to scale than the photo-sharing feature in their chat client that was extracted to base their final business on.
Twitter's original codebase started as a "my first blog" tutorial in Rails — the polar opposite of a messaging platform. That's a hell of a ship to turn around, especially live on the world stage while the userbase and datastore are growing exponentially and you're rapidly approaching the second half of the chessboard.
Facebook both very intentionally limited their growth (new colleges) and avoided their most expensive features (like photos) for as long as possible. Flickr was originally an open-ended MMO/MUD based on user-contributed content called Game NeverEnding, which was far harder to scale than the photo-sharing feature in their chat client that was extracted to base their final business on.