The Killer 2100 shows some improvements over the integrated Intel 82567LF-2 network controller in our test rig, but the difference is so slight as to be almost impossible to detect in real terms.
We did see a small boost in the framerates in Lead and Gold, but it was hardly game changing.
In World of Warcraft the framerates were untouched, but the latency did improve. Unfortunately the results were significantly slower than when using a common tweak that disables the Nagle algorithm to boost TCP/IP performance.
MMO gaming latency