It slows down when an "oversized" control is placed in it because the entire control will be rendered.
Very easy to reproduce with:
RscStructuredText
RscEdit
RscListBox
It slows down when an "oversized" control is placed in it because the entire control will be rendered.
Very easy to reproduce with:
RscStructuredText
RscEdit
RscListBox
Structured text won't be fixed.
Check if your other cases are fixed on performance/dev-branch