It's plenty unless you're sharing it with multiple people. You're more likely to get slowdowns from the remote server or because your computer has to interpret a zillion layers of JavaScript.

Also check that you're getting the service you pay for. Most plans are "up to" N Mbps. It's pretty common to get 3 Mbps down on a nominally 10mbps connection. Cable internet in particular is prone to congestion in densely populated areas if the ISP hasn't installed sufficient bandwidth. And assuming you're using wifi, signal strength/quality/interference can affect your download speeds as well. There are plenty of tools available to investigate that.