I've seen multiple sources claiming that CoD2 and WoW run with better FPS on Wine for example.
https://wiki.winehq.org/FAQ#Is_Wine_an_emulator.3F_There_see...
Also before it changed its name for the current retro acronym WINE used to mean WINdows Emulator: http://www.faqs.org/faqs/windows-emulation/wine-faq/
However, Wine is not an emulator in any way like the way that word is used in technology.
Any software that is around 15 years or older has a really good chance of running, I would say even more than Windows 10.
Newer DirectX 9 games, specially with the wine-staging patches, have a good chance of running, but nowhere near what current Windows can attain.
Anything newer with DirectX 10, 11 or 12 is pretty much a train-wreck. Unless the game runs OpenGL or Vulkan, like DOOM 2016, which after removing the DRM and some patching from devs runs like a dream.
Unless you run wine with the gallium-nine patches (which implements DirectX 9, 10, and parts of 11 natively on top of the gallium driver system, providing native DirectX performance on AMD and the open source nvidia drivers).
Sadly, the wine maintainers prefer their ugly hacks for their DirectX implementation, so it’ll likely never be merged.
As a general rule, assume that there will always be a performance penalty. It will be good enough to be playable, but you'll notice the difference, and you'll have to adjust the graphics down one or two notches (go down from "Max" graphics settings to "Medium" or similar). If you can live with this, you're fine.
Some games, in particular old games that don't rely much on 3D (I'm thinking of Age of Wonders right now), work really well, or well enough that you don't notice the difference.
I have some games that are unplayable, but thankfully those are rare (or I am just lucky). X3, for example, is glitchy as hell and the performance is very bad. Some games are also inexplicably slow: there are some PopCap games (very casual and "lightweight" games) that are just unplayable, for some reason.
However, with regards to being playable, I think that the graphical bugs will be the showstoppers, not performance.