I notice that the Juce VST wrapper determines the size of the GUI by creating the entire GUI and reading the size of the Component. I find that being a bit of an overkill; especially when you would load a lot of graphics during setup. It would be a lot of memory allocation for fetching just two integers: width & height, two numbers you know as a developer anyway.
The final creation of the GUI begins by deleting the editor that was created just millseconds ago.
I suggest this unnecessary procedure should at the very least be proceeded by some sort of GetGuiSize() call.