Same issue for me.
Saving is ok, but it's the reload of the just saved page in backend that it take such a long time (up to 30 secs for somes)
I don't really remember, but I think this is since a particular rev of the lscache plugin.
If I find which one, I'ill edit this post.
I just replied webmastergreg's Github issue, there is no need to patch virturemart for the 3.2.2+ virturemart versions.
About the slow reload after save a product, it might because you enabled auto recache after saving feature in plugin settings, it will crawl all expired cache copy after saving a product or a category. if it is not that case, please submit a ticket or send your website information to firstname.lastname@example.org .
But it might be better if the recache process doesn't prevent you from regaining control of the product sheet being edited once saved, isn't recache supposed to be a process that can take place in the background?
This has nothing to do with the fact that a background process could solve the problem. The suspected cause is that the session and the data are locked as long as the recache process is not completed. This can be solved comparatively easily, but the plugin would have to be changed for this. I can't rule it out entirely, but it could also be Joomla itself and that will inevitably affect how the plugin works.
Unfortunately, I can only give you a limited explanation of the possible cause because I don't know the code of the plugin. But from the description of the problem, there is a lot to suggest that I'm right.