Performance tuning, especially in cellular and wireless networks, is one of the most important issues in TCP/IP. You will nee to change the performance parameters in various cases:

• When your network becomes slow, and your WAN connections does not meat the network requirements. In this case QoS definitions an some applications settings are required
• When you are a cellular provider, and your customers complains about slow performance while using the network. In this case you will need some adaptations to of the TCP/IP protocol stack to the cellular environment. That includes PEPs (Performance Enhancements Proxies), Application Accelerators and more
• In case that specific applications wirks slow, and other works fine. In this case, some applications tuning is required