Seems to be super slow if the text size is large. Also does not display the whole text. Much slower than this https://forum.renoise.com/t/new-tool-3-0-instrument-comments-editor/41390
That tool is using the API to set the text, plain and simple. So I’m not sure what you mean by super slow.
You have to be careful - avoid modifying values in the array, one by one. Instead, prepare and replace the entire array in one go?