When using widget, malformed URLs (2) are generated (major slow down)

I think this should be repeatable. I’m using a very simple list view calendar and pulling that into the provided widget.

As soon as I add the widget, there are two calls made on every page load to https://h/?ver=3.1.10. These obviously fail to resolve, but they dramatically slow down the rest of the page loading.

Here’s a link to a screen shot of the Chrome developer tools.

I’ve replicated the issue on an extremely simple development WordPress install in the same server environment. I recreated all the calendars from the production site and things worked fine. I added the widget with the recreated list calendar and immediately started getting the errors on that site (used Customize panel so I saw the errors pop up in Dev Tools almost immediately).

I haven’t dug into it much more yet. I wanted to post the bug once I isolated the seeming source.