System slowdown when Wi-Fi enabled

Wi-Fi is naturally slower, and then a wired connection. The bandwidth is also less. Then note that, the Ethernet signal to go through a pair of transitions when using wireless. Ethernet to RF = Radio Frequency back to Ethernet. Upgrading to wireless N can help. Also some may not report problems using wireless for gaming. The reasons for the problem (s) that the experience can be numerous. Some are beyond your control. Even outside RF interference from other devices. Microwave ovens, cordless phones, certain types of lighting are the few names.