Linux gaming is getting faster because Windows APIs are becoming Linux kernel features
(www.xda-developers.com)
It's not a scheduler issue, it's a windows apps do thread synchronization differently to linux apps. Additionally fsync in the vast majority of use cases works just fine, the article notes most performance comparisons are against vanilla wine synchronization, i.e. without fsync or even esync. Regardless I still don't think the kernel should be emulating windows scheduling behavior.