Very slow performance with Second Life viewer

[John Nagle]

I'm seeing momentary stalls running the Second Life viewer under Wine.

* Wine 7.0, Ubuntu 20.04 LTS
* Not even close to being out of memory. 10GB of 32GB in use for the system.
* Not running out of CPU time; total CPU utilization stays below 25%. 6 cores, 12 hardware threads.
* NVidia 3070 GPU.
* Profiling tools built into the viewer show that almost all the time goes into the viewer's Render section, but none of the subsections below that show much time.
* Vsync in the viewer can be turned on and off without changing much.
* Occasoinal frame stalls as long as 1 second. 0.5 sec stalls common.

Are there any Wine tuning parameters I need to adjust?