In InDesign 18.0 on Windows 10:
When I have a document open that has a lot of hyperlinks in the text and the Hyperlinks Panel is open, InDesign becomes unusable, because it constantly keeps checking the validity of the hyperlinks as a foreground process. So it keeps hanging and on the spinning blue circle. As soon as I manage to close the Hyperlinks Panel the problem dissapears, but sometimes I actually need to use the hyperlinks panel, and then the problem is back again. It becomes almost impossible to do/click/select anything in InDesign at that moment. This needs to be fixed, and the hyperlink validation needs to be a background process again!!!