[Bug 48293] New: Battle.net App lags when clicking UI elements

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=48293

Bug ID: 48293
           Summary: Battle.net App lags when clicking UI elements
           Product: Wine-staging
           Version: 5.0-rc1
          Hardware: x86-64
                OS: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: -unknown
          Assignee: [e-mail]
          Reporter: [e-mail]
                CC: [e-mail], [e-mail]
      Distribution: ---

This is a regression between 4.21 and 5.0rc1.
On 4.21, clicking UI elements (e.g. Play button, friends list, or most
noticeably selecting different games) was smooth and quick. On 5.0rc1 there is
a 1-2 second lag after clicking when the whole UI is not responsive.

Reproduces both on NVIDIA (GTX 1060 with proprietary driver) and AMD (RX 560
with Mesa).

I've tested in a clean prefix, and narrowed it down to be between Staging
commits 4522654f and 45d69ec4:
Ok?   Wine        Staging   wine --version
good  5f0b5d3505  4522654f  wine-4.21-347-g5f0b5d3505 (Staging)
BAD   750d382f54  45d69ec4  wine-4.21-413-g750d382f54 (Staging)
I'm currently doing bisection of Wine commits between the above two versions.