There could be a number of reasons why the Internet might appear to be slow, however here are a few of the likely issues and things to check:
1) Under the Tools menu, check the port speed to make sure that it is syncing correctly with your WAN device (router/modem/etc), you want to see a good link here. If there is not a good link, you will need to hard set the port speed on the WAN port and the associated device.
2) Check to make sure that there are no errors on the link, this can be done by performing an AutoSense test and looking for any errors in the report it produces.
3) Setup a Best Path Routing rule with SLA reporting enabled. This will generate a report for each WAN link which can be used to determine if there is a link problem with your ISP.
4) Make sure that the Rate Limits for each WAN link are set correctly. The default is 10Mbps so if you have faster link rates, make sure these are set correctly.
5) If websites are slow to load, this is commonly a problem with DNS and link bonding. Make sure that you have a DNS IP address for each of your service providers entered under the LAN interface configuration tab. This is very important to ensure the fastest possible speed.