For those of you who want to get every bit of performance from your AT&T Galaxy S2 (SGH-I777), you might want to think about overclocking your phone to 1.6Ghz from the stock 1.2Ghz.
This can be good for 3D gaming and other instances where CPU performance might be in need.
To overclock, you will need an overclockable kernel, you can try my Zedomax OC Kernel, which allows you to overclock up to 1.6Ghz. (or 1.4Ghz too)
You will need an app like SetCPU (available on Market or google it) or CPUMaster to actually overclock.