The most common reason that users face this problem is due to their connections to the internet being slow.
If you find that any site you access from your browser is slow, you may contact your provider asking them to check the connection or if you are using a dial-up you could have your phone lines checked.
The other common reason is network congestion caused due to too many people all trying to reach the same services at the same time.
It could also be due to specific environmental conditions that determine the connection speed or possibly our servers may be facing a temporary problem.
These are temporary conditions and often get cleared soon. At such times you could try accessing the site after a short interval of time.