Clicking on large folders/listing a large amount of pins stalls the UI

**Describe the bug**
The UI cannot handle long lists of items

**To Reproduce**
For me listing my 6k pins doesn't work. The UI just stalls and works endlessly on this task, until chrome asks to close the page.

**Expected behavior**
Just the first two dozens or so items are fetched and displayed. Since the total number is already known, they could be shown as pages.

Also, operations that take longer than something like 1 second should get a progress bar and not stall the browser tab. There should also be an abort button.

**Screenshots**

**Desktop (please complete the following information):**
- OS: Linux
- Browser Chrome
- Version 79