Created attachment 148527 [details]
Valgrind of a session running over NX technology.
In testing version 6.2, it was noticed there was a big performance issue at cold start. 6.1 is opening in about 2 seconds, and 6.2 takes about 5-6 seconds before it's fully rendered.
If the VCL is changed from default GTK3 back to GTK2, it immediately gets much faster.
We have many other GTK3 apps running and are not seeing any performance issues this badly.
LibreOffice is being run from large multi-user servers using the NX Xserver. Your larger enterprise customers may have similar issues as they move this version live. This technique is similar to using VNC to run an Xserver, and it's possible the performance issue would be seen using this software as well.
In the past, when these types of things happen, the local video card of the computer is compensating for the issue so it's not noticed.
When LO opens, the initial canvas appears and then slowly the icons and pulldown menus appear when in GTK 3.
I did a valgrind and will attach. Not sure what else I can do to help.
Noted, this is on Linux.
Dave, how familiar are you with bibisecting? 
This could probably be bibisected with repo bibisect-linux-64-6.2 .
@Aron: I have done a bibisect before. I'm not sure it's appropriate here because I don't think the GTK3 VCL ever worked correctly. In versions <= 6.1, it defaults to GTK2. With 6.2, it's defaulting to GTK3 as I understand it.
I think there is a low level performance issue here. If we can solve my issue, we should also get a nice boost even for those users with local video cards.
Indeed, I didn't notice there was a switch between 6.1 and 6.2.
Any update with 6.2.4? Do you still see this perf issue in gtk3 compared to gtk2?
Also, Valgrind is used to find memory management pb. I supposed you'd need callgrind or Flamegraph?