At dnd from Palette to page editor with Ctrl pressed, text to be inserted is generated without displaying wizard. The current solution is simple and reliable: create dialog, create all widgets in wisard, and call performFinish() without making the dialog visible. After text generation without creating UI in wizard is implemented in JBIDE-17084, implementation of dnd with Ctrl pressed should be switched to it to improve performance.
Comparing generation based on invisible dialog and generation based on wizard without UI shows that the time of generation is about 20 times less in the second case.