What is the “Processing…” message?

[nsk]

I get this message while reviewing sometimes. What does it mean?

[Danika_Dakika]

How to find out what Anki is "Processing..."?

It will pop up any time a long-running operation takes longer than about 600ms to complete. This could be because some other long-running action was already running, or because your machine’s disk is temporarily slow (because of other background activity)

If you’re seeing it frequently, go through the Troubleshooting Checklist and see if you can isolate what’s causing it.