Thank you for noting your observation.
Having a RibbonBar somewhat slows down the speed at which newly-typed symbols appear in the RadRichTextBox. This is due to the fact that RibbonBar (or RadRichTextBoxRibbonUI) subscribes to events that typing in the Document fire, in order to change their state (e.g. the Bold button appearing as pressed if the caret is placed in a bold span).
We will look into the issue and improve the performance and responsiveness for the official release.
If you have any other questions, feel free to contact us again.
the Telerik team
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