The Batman game moved from 30.7 fps at Medium detail to 38.0 fps, or a 24 percent increase in framerate. At High detail a similar increase shifted average framerate from 30.3 to 36.0 fps, or a 19 percent increase.
For Tomb Raider we first toggled on the Legacy OpenGL option in this game to obtain playable framerates, since the game's default uses the latest OpenGL API which drastically reduces framerates on slower graphics processors such as the Intel Iris Graphics 5100.
At Normal detail the results were effectively the same between OS versions (22.1 to 22.0, or 0.45 percent drop) while a shift to High detail restored the earlier trend with a 4 percent framerate increase in Yosemite, even if that only resulted from a smaller than 1 fps difference, from 21.0 to 21.9 fps.
Unigine Heaven also benefited very slightly in our Yosemite Mac, moving from 20.5 to 21.6 fps, or a 5 percent increase.
The GFXBench test we use for iOS and Android devices is now available for OS X, and this suite of tests showed some interesting differences.
In a nutshell: When testing with real-world games, we saw noticeably higher gaming framerates on Yosemite, with the difference varying between 4 and 24 percent.
Mavericks vs Yosemite speed testing: GFXBench graphics tests
The first Manhattan test gave an average framerate of 14.62 fps in Mavericks, and 13.20 fps in Yosemite, or a 9.7 percent slower framerate. The same test ran offscreen had a smaller difference, 28.04 down to 27.73 fps, or 1.1 percent slower in Yosemite.
Bigger, much bigger differences were recorded in the next test using the T-Rex animation. Mavericks averaged 47.22 fps onscreen, while Yosemite gave us an average of just 30.42 fps. That's around a 35 percent drop in framerate for the newer OS. Offscreen rendering followed suit, from 87.98 fps in Mavericks to 55.5 fps in Yosemite; or a 37 percent drop.
The ALU test measures shader compute performance, and here the last and current OS gave the same effective result, at 59.99 and 60.00 fps onscreen; and Yosemite pulling ahead with off-screen rendering (338.5 to 349.7 fps, or 3.3 percent improvement).
The remaining results showed some odd trends. In the Alpha Blending test, on-screen renders were within 1.5 percent, 4379 MB/s to Mavericks and 4312 MB/s to Yosemite. But using an off-screen 1080p mode the drop was precipitous, from a steady 5617 MB/s in Mavericks to wildly varying numbers in Yosemite, from 3050 to 1399 MB/s, with a mean at 1899 MB/s. That's a 66 percent drop in performance.
The Fill test had a poor showing with Yosemite in both on- and off-screen modes: Maverick's 7002 MB/s down to 4685 MB/s, and 7302 MB/s down to 4171 MB/s - with high standard deviation in those Yosemite results too. That equates to 33 percent and 43 percent drops when moving from 10.9 to 10.10.
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