Doom likes to run fast, and especially so with a GTX 1080 pushing pixels. The game's Vulkan mode is an especially hard test for keeping that beast of a graphics card fed. We cranked up all of Doom's eye candy at 1920x1080 and went to work with our usual test run in the beginning of the Foundry level.
Doom's Vulkan renderer generally runs well with most any reasonably capable CPU, but our results do turn out a bit oddly regardless. The Core i3-6100 comes out on top, while the Ryzen 3s land midpack. The Kaby Lake Core i5-7500 and i3-7350K have a much harder time with Doom than we would have expected.
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. The formulas behind these graphs add up the amount of time the GTX 1080 spends beyond certain frame-time thresholds, each with an important implication for gaming smoothness.
The 50-ms threshold is the most notable one, since it corresponds to a 20-FPS average. We figure if you're not rendering any faster than 20 FPS, even for a moment, then the user is likely to perceive a slowdown. 33 ms correlates to 30 FPS or a 30-Hz refresh rate. Go beyond that with vsync on, and you're into the bad voodoo of quantization slowdowns. 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 Doom can easily meet or surpass on hardware that's up to the task. For that reason, we've also added a button for the 6.94-ms mark, or 144 Hz.
None of the chips here give the GTX 1080 any significant trouble at the 16.7 ms or 8.3 ms thresholds, so mash that 6.94 ms button and have a look. Even at this demanding threshold, the Ryzen 3 1300X only perturbs the graphics card for about two seconds of our one-minute test run, and the Ryzen 3 1200 makes it spend about three seconds working on frames past the 8.3 ms mark. Both Ryzen 5s cut that figure down even further, while the i3-6100 seems to have had a lucky day in our test rig, or something. This data doesn't tell us why our Kaby Lake chips had so much trouble running Doom, relatively speaking. Still, all of these CPUs provide a pleasurable gaming experience in Doom under the Vulkan API.