Windows APIs have a whole operating system to support, including all the new features. Microsoft rarely breaks backwards compatibility (so no 'sacrificial' APIs), but that doesn't mean there couldn't be some performance regressions or the like under newer versions. Windows went as far as changing COMMCTL32.DLL and similar just because of new Office versions.
Wine "only" has to run apps and nothing else. The older APIs are the most battle-tested and optimized. On the other hand, you may find suboptimal behavior on newer APIs that weren't exercised enough.
Wine "only" has to run apps and nothing else. The older APIs are the most battle-tested and optimized. On the other hand, you may find suboptimal behavior on newer APIs that weren't exercised enough.