https://bugs.freedesktop.org/show_bug.cgi?id=101325
--- Comment #6 from Luke dodgyville+freedesktop@gmail.com --- Here is a dropbox link to the gzipped output from apitrace trace.
https://www.dropbox.com/s/u224vlazdql774j/UE4Editor.5.trace.tar.gz?dl=0
I feel like perhaps the ddebug_dumps file might be the most useful thing as those environment variables had a material effect on the issue?