The funny thing about Joplin sync being too slow... years ago, I complained to the author that his markdown files weren't true markdown, and his rebuttal was that it was necessary to pollute those to get sync to perform well on Nextcloud/webdav. I pointed out how he might have just written a small NC plugin to achieve the same effect, at which point the thread was closed and I was no longer welcome to comment.

Maybe that's changed since though.