Macbook Pro late 2011 WiFi issues

Question

Hey guys and gals,
I've been having some issues with my late 2011 Macbook Pro 17 inch. It has been loading webpages very slowly on some occasions. About 50-60% of the time it runs almost perfectly, but sometimes it just starts loadaing various websites very slowly and can take up to 5-10 mins to load something ir it may not even load it at all. The weird thing is, it goes back to working normally after a few mins. It also loads .gif images sowly most of the time or it may play them frame by frame and then freeze them, where as my dads 2009 Macbook Pro 17 inch loads them instantly and perfectly.
I thought it was just a problem with my internet so I had them check my line and give me a new router. The line was fine and the router has a slightly better signal than my last one but the problem is still there. My Dads Macbook Pro doesn't seem to encounter the same problem even though I've been using it all day flawlessley.
What could be causing it? What might the solution be? Any help is greatly appreciated.
Jamie.

Answer 1

Some users with various Wi-Fi connection problems have reported that they were given the following instructions by Apple Support, sometimes with success. I can't vouch for this procedure myself. After completing the procedure, you'll have to recreate all your settings in the Network preference pane. Make sure you know how to do that before you begin. Taking screenshots of the preference pane may be helpful.
Step 1
Back up all data.
Triple-click the line below on this page to select it:
/Library/Preferences/SystemConfiguration
Right-click or control-click the highlighted line and select
Services ▹ Reveal
from the contextual menu.* A folder should open with an item named "SystemConfiguration" selected. Move the selected item to the Trash. You may be prompted for your administrator password.
*If you don't see the contextual menu item, copy the selected text to the Clipboard (command-C). In the Finder, select
Go ▹ Go to Folder...
from the menu bar, paste into the box that opens (command-V). You won't see what you pasted because a line break is included. Press return.
Step 2
Reset the System Management Controller