TextEdit 1.15 is very slow on Catalina.
(E.g., the long latency on open; the remnants of a textual mirage; the cursor circling in wait state.
Previous versions of a MacOS I don't recall having such poor response time.
Is it just me?
Try updating to 10.15.3 and to the latest version of TextEdit as well. If not, submit reports with both Apple and the app's developer for good measure.