SG TCP Optimizer
At first glance, the program is daunting, because of the amount of technical detail you appear to need to know in order to use it, such as Latency, Largest MTU, and so on. Your best bet is to click the Optimal settings button at the bottom of the screen, and then click Apply changes. That way, the program decides on its own the best settings and applies them. Unless you're very experienced, you probably don't want to muck around with the settings yourself.
Keep in mind that the proper connection settings can vary significantly from PC to PC. So there's a possibility that you can change your settings and could slow your system down. Mostly, though, if you follow the advice you'll find yourself with a better connection, not a slower one.
Note: This download takes you to the developer's site.