Project Cars is beautiful. I could race around Road America in a Formula C car for hours and be thoroughly entertained. In fact, that's pretty much what I did in order to test.
Click the buttons above to cycle through the plots. We capture rendering times for every frame of animation so we can better understand the experience offered by each solution.
Whoa. That's different.
So, first things first: the Skylake 6700K takes a clear lead over the Haswell 4790K with a markedly higher FPS average. The differences are a little smaller if you switch to a more advanced metric like our 99th-percentile frame time, but either way, Skylake beats Haswell cleanly.
Things get weird, though, with the Core i7-5775C in the picture. The Broadwell-based CPU with the 128MB L4 cache turns in the top performance in Project Cars, outdoing even Skylake. Looks like that big cache can help with gaming performance, even with a discrete GPU.
We can understand in-game animation fluidity even better by looking at the entire "tail" of the frame time distribution for each card, which illustrates what happens with the most difficult frames.
These "time spent beyond X" graphs are meant to show "badness," those instances where animation may be less than fluid—or at least less than perfect. 16.7 ms correlates to 60 FPS, that golden mark that we'd like to achieve (or surpass) for each and every frame. And 8.3 ms corresponds to 120 FPS, an even more demanding standard that may become more popular with the growing popularity of PC displays with high refresh rates.
Someone told me Project Cars was seriously CPU-bound. Maybe that was true in older versions of Windows. Maybe Win10 has introduced some magic that changes the math. I dunno. What I do know is that even the slowest CPU here, the FX-8370, spends less than half a millisecond beyond our 16.7-ms threshold. In other words, that CPU pumps out frames at a constant 60Hz throughout almost the entire test run. The faster Intel processors aren't too far from delivering a constant 120Hz.