Hello omihubert,
Based on your post I understand you are experiencing slow network speeds. You may want to consider creating a new network location. A new network location creates fresh network settings which can sometimes solve issues such as sluggish speeds:
OS X Mountain Lion: Add a network location
A network location is a group of network settings for your various network services (your computer’s Ethernet port, modem port, and AirPort Card, for example).
If you often change network settings, you may find switching between locations quicker and easier than repeatedly modifying individual groups of settings.
For example, you might want to make a location for “home,” where you connect to the Internet with a telephone modem, and a location for “office,” where you connect to your company network and the Internet using Ethernet or AirPort.
- Choose Apple menu > System Preferences, and then click Network.
- Choose Edit Locations from the Location pop-up menu, and then click Add (+).
- Enter settings for each network connection service you want to use in that location.
After you create your locations, you can switch all of your network settings by choosing a different location from the Location pop-up menu.
Keep in mind that you will have to re-enter passwords for networks you've already joined. If that is an issue, you can switch back to your original network location at any time.
Thank you for contributing to Apple Support Communities.
Cheers,
Bobby_D