https://bugs.winehq.org/show_bug.cgi?id=42261
--- Comment #5 from winetest@luukku.com --- (In reply to C0rn3j from comment #4)
The lag seems to be completely gone under wine-staging with CSMT ON.
Are you aware that wine 2.6 now includes CSMT patches? It's off by default.
See this guide CSMT part
https://wiki.winehq.org/Useful_Registry_Keys
So could you test if this helps?