“If your site is taking 20 or 30 seconds to respond to requests, that could be a problem...” — Matt Cutts, Google

Search engines won't send people to your site if they can't even connect. So make sure your site is hosted on a working web server.

If search engines can't reliably connect to your site whenever they want, then they can never be confident about sending people to your possibly-offline website. So don't just get a server that usually works; get a web server that's very reliable.