https://bugs.winehq.org/show_bug.cgi?id=41107
--- Comment #14 from katsunori.kumatani@gmail.com --- Not sure if this will help but I stumbled on probably the same bug applied in a different situation.
If you use Winamp with the Enhancer 0.17 plugin (a really old one), just by having it open, it will slow down certain tasks in every other application on the same WINEPREFIX! For example, enumerating/going through lists in Total Commander (files and folders) gets slowed down by just having Winamp with the Enhancer plugin up (even without playing). This slows down applications in the same prefix that use Windows "trees" too (those lists that you use + sign to open subtrees etc, not sure how they are called) when attempting to go through those trees etc.
The problem goes away if I start Winamp in another WINEPREFIX (thus different wineserver) leading me to believe it's the same bug, since Winamp is affecting the wineserver which waits because of the bug.
Sorry if I sounded dumb, it's probably way over my head to understand why it does that. :)