Test this a bit more: when I paste a paragraph-length rem into a document, Remnote also refreshes/reloads the Source section of all open panes, as well as the Sidebar. I’m not clear why it would influence the other documents. The scrollbars and top part of the Panes are reloading/refreshing also. So then the summary is that several UI element are refreshing/reloading when I type. The longer the pasted text (10 sentences vs 3 words) the longer the reload takes.
I changed the title of this topic, to reflect that more elements than the Sidebar are reloading.
Update #3: I tested this some more. It seems those UI elements disappear during the duration of my typing in a document. Then when I quit typing, they come back. As for me, I don’t mind seeing them while I type, and the going-away-coming-back is not needed.