Make Internet Connection Faster on Mac OS X Leopard
From Mac Guides
Method 1: System Preferences
1. Launch System Preferences
2. Under the "Internet and Network" category, select "Network"
3. Click the lock button near the bottom of the window (if needed) and type in your password. This is only if you have the lock, locked.
4. Then click "Advanced"
5. At the top, select "TCP/IP"
6. Then find "Configure IPv6"
7. Click the drop-down menu and select "Off"
8. Save your settings and exit System Preferences
Method 2: Terminal
1. Open Terminal
2. Type in/copy and paste the following commands (one by one)
sysctl -w net.inet.tcp.recvspace=65536
sysctl -w net.inet.tcp.sendspace=65536
sysctl -w net.inet.tcp.delayed_ack=0
3. After typing in the first command, type in your password (Please note that you will not see any characters in the Terminal windows as you type your password)
4. Run the remaining commands. When you hit exit, the commands entered are closed and you can close the Terminal window.
Congratulations! Your Mac should see improved Internet speed.