As Michael noted, running local will be faster - however, we've had no problem running a heavily used roundcube system on a server outside of the mail server's local network and it should not be a huge performance issue (because, essentially, this is what a user does with a desktop mail client anyhow). If your web server has a good capacity to handle an application, you should be just fine, and I don't see one as being a huge increase over the other depending on your system.
If you want to gain a very small performance speed, use the IP of the mail server rather than it's DNS name if your mail server will allow that communication (that's assuming roundcube will accept it and your mail server is housing only your mail) - avoiding the translation of DNS to IP will give a performance increase... but again, very small, so only if you're really cramming for performance.
Kenn Murrah wrote:
Greetings.
Is it generally more efficient to run roundcube on the same server as the email (IMAP) server, or is it better to run from a different server?
Thanks.
kenn