For Switchboard's intended task of as-they-arrive email processing, speed is not a huge issue. That being said, there are plans for using more than one IMAP connection to parallelize some requests.

Switchboard is fairly different from context.io. Switchboard is open-source -- being able to keep in control of services accessing emails on your users' behalf is great. Also, Switchboard is intended for processing emails as they arrive using worker processes, as opposed to context.io which appears to be primarily a proxy.