Often times your site may seem slow the first time you view it, and then it's faster afterwards. This is common on low-traffic websites and is due to the default setting on the server to shut down your site's application after it doesn't receive any traffic for 20 minutes. When someone first views the page after that, it will seem slow on the first visit. To get around this on low-traffic websites you can use a ping service to keep your site alive.
You can run a free program available at http://help.smartertools.com/SmarterPing/v1/
An alternative to running a service on your computer to perform this function is to use a service such as http://host-tracker.com/ which will ping your site as often as you tell it to and email you about any outages. This service may have a fee associated with it after a trial period, so it's entirely up to you.
If you have a dedicated or VPS server, you can view this article about modifying the application pool settings of the website.