Like the first part, Left 4 Dead 2 benefits a lot from a fast CPU. PC Games Hardware ran benchmarks with twelve processors.
Left 4 Dead 2: Introduction and Engine
Left 4 Dead 2 (4) [Source: view picture gallery]
Although Valve once again used the Source engine for Left 4 Dead 2, the developers nevertheless modified the structure for the new game. According to Chet Faliszek, inventor of Left 4 Dead, the developers enhanced for example the shaders, the lighting, the particles and the water. Multi-core support, diverse (Post) effects like Color Correction, Motion Blur and FP16-HDR as well as Film Grain are still integrated. Due to Soft Shadows, Self Shadowing, Normal Maps and Wet Surfaces the sceneries appear a little more realistic than before. The Havok physics engine top the technical features of Left 4 Dead 2 off.
Left 4 Dead 2 (10) [Source: view picture gallery]
Left 4 Dead: Benchmark sequence and results
Left 4 Dead 2 (9) [Source: view picture gallery]
For our benchmarks we use a 60 second real-time demo sequence which takes place in the park from the second chapter of the "The Parish” Campaign. In the scene we have several Bommers and a Splitter as well as a lot of ordinary enemies. We use a Radeon HD 5870 to display the demo at 1680 x 1050 with maximal details and with as well as without 4x MSAA and 16:1 AF. So all in all the setting is quite challenging for the CPU. We are using the German cut version which runs about 40 percent faster than the international uncut version.
Left 4 Dead 2 benefits a lot from three respectively for cores and thus an Intel C2Q Q6600 is, without AA/AF, almost 45 percent faster than its dual-core counterpart, the C2D E6600. With 4x MSAA/16:1 AF the difference isn't lowered much. An AMD Phenom II X3 720 BE finally is fast enough to run into the graphics limitation (about 130 frame per second on average) - faster CPUs only increase the minimal framerate. As you can see from the results without AA/AF, the Phenom II CPUs are doing quite well and the X4 965 BE is on the same level as the Intel Core i5-750; the X3 720 BE is only slightly behind the Q9650 while the X2 550 BE beats the C2D E8400 noticeably. A Core i7-920 running at 3.5 GHz (Uncore at 2.8 GHz, DDR3-1400) can't really distance itself from the rest - it reaches a max fps results of up to 300 which actually is the engine limit.
Although Left 4 Dead 2 benefits a lot from more than two cores, you are well equipped with a processor like the C2D E6600 or the X2 6400+. Only during the final wave of infected, the framerate drops below 40 fps. So if you want to play Left 4 Dead 2 smoothly in any critical situation, you should have a C2Q Q6600 or a Phenom II X3 720 BE or a faster processor. Intel's SMT does not slow down the game, but doesn't increase the performance either.