Document Library Views with grouping by property is extremely slow in Modern experience

We are experiencing extremely slow page loading in document libraries when the default view is grouped by one or more columns (in our case, managed metadata columns). 

For example, a library view which groups first by MMD column 1, then MMD column 2, with approximately 300 documents, takes around 30 seconds to load.

Is this expected behavior in the modern experience? I do not recall views such as these being an issue in the classic SharePoint experience.

Thanks for any feedback/advice.