It isn't a messy code in cod in terms of cpu. He simply has much to calculate and raw power in newer cpus just help to avoid a cpu bottleneck. As I haven't benched clod in terms of cpu usage, I cannot say much, but it seems, that generally over 3.5 ghz in a quad core is enough so far. It bottlenecks, if you put a lot of objects in it, especially many ai pilots. As the calculation of ai pilots uses one core, it simply bottlenecks, if it gets too much. There is a very new thread of one guy having a real high end system and he tells, that his cpu bottlenecks on about 40 ai planes? Correct me if I am wrong.
U can say, that the capability of nowadays cpus to get overclocked is quite good and affordable for nearly all sims and games with a lot of traffic and big landscapes with a lot to compute.
Casual games like bf3 will work quite fine at your stock speeds or a little higher. Anf this is only, because the most physx, you see in games, is managed by the cpu. There are just few games using the gpu for physx calculations. For me personally a poor development, but non of the casual gamers are asking for better detailed physx, which I definetly would do!!!
So, overclock your cpu to 3.6 ghz and it should be good enough. I cannot give you a workaround as I also simply hit the switch with my watercooling without any tweaks at first. I have enough room with watercooling to do it like that, but I am now also tweaking for better behaviours of my cpu.
I will not directly say: do it and just hit the switch in bios. But i did it that way first
disable ht, disable turbo mode and gave him a constant clock with the help of a tweaking guide, which referred directly to my cpu, stepping and serial number.