Just came across a very repeatable crash. A new document with the top row simple some text with the .todo. After the .todo, try to a a tag and the program will freeze with some intermittent activity. The only remedy is to close that document and open a new one. Extremely repeatable. Some testing shows that the Styled Tags.ftplugin is the culprit. I like that plugin, but not this behavior. The package file says it is from https://github.com/pryley/styled-tags-for-foldingtext.
I added an issue to the GitHub account as well.