New World of Warcraft Optimizations Send DirectX 12 Performance Soaring

For a 14-year-old game, World of Warcraft has continued to evolve and grow at a surprising rate. Earlier this year, the game added DirectX 12 support as part of the run-up to the launch of its current expansion, Battle for Azeroth. We benchmarked the addition at the time but found the change to be of minimal value on both AMD and Nvidia hardware. Nvidia GPUs performed sharply better in DirectX 11 mode (which isn’t surprising) but even AMD cards were hitting higher minimum frame rates in that API as well.

can test it on ptr now. enable dx12, then play with the MT cvars. set all to one except for the disable. but once you enable the 4 MT renderers, you can use disable to toggle diff between non MT and MT. especially check it out on boralus. :D pic.twitter.com/CxvR1raf21

— ????????Adam (@MysticalOS) October 6, 2018

There are now four additional flags for multi-threaded CPU optimizations that users on the PTR (Public Test Realm) can set and experiment with, including Apple users (Metal support, apparently, is also included). WoWhead took the game out for some testing in Boralus, the new capital city of the expansion for the Alliance, and saw some interesting results. The test itself was primitive — standing only, with DX11, DX12 (standard) and DX12 (with new optimizations enabled at the same time).

The game was tested in 1080p with 8x MSAA on a Core i7-8700K overclocked to 5GHz using an Nvidia GTX 1070 and 32GB of DDR4-3200. The improvements are… substantial.

Even better, they carry through to 4K, though WoWHead didn’t graph those figures. For 4K, however, a Core i9-7980XE was used, paired with a GTX 1080 Ti.

These are truly impressive gains at 4K — though they also imply that WoW has been leaving a great deal of performance on the proverbial table. We’d expect 4K to show relatively smaller performance enhancements simply because at that resolution, most GPUs aren’t being tripped up by waiting on the CPU any longer (as we’ve discussed before, DirectX 12 is more of a performance improvement for low-end CPUs than a direct boon for lower-end graphics cards). At least, that’s been the typical thinking. But a six-core Core i7-8700K at 5GHz isn’t anyone’s idea of a low-end CPU — and WoW is picking up major performance. A 23 percent gain for the 1080 Ti is still quite large relative to what we’d expect to see in 4K.

As always, keep in mind that how much performance you pick up in DX12 will always be a function of your GPU architecture. We don’t know yet how these gains play on AMD cards or if Maxwell GPUs from Nvidia can benefit (if you have to bet, it’s safer to bet they won’t). But we’ve been meaning to revisit WoW to see how the DX12 update was coming along — once this patch goes live on the main server we’ll have to pay another visit to Azeroth to see how things are shaping up.

The two features already enabled in DX12 by default are gxMTBeginDraw and gxMTShadow. The two new functions you can test on the PTR are gxMTPrePass and gxMTOpaque. Instructions on how to set these variables and their results can be found on WoWHead. The updates will arrive in Patch 8.1, Tides of Vengeance.

Hat-tip to Twitter user Nyn, who notified us about the improvements.