There was a client bug which caused it to be slower than intended with polling the API for the progress of server processing, in the case of your avatar would have meant 30s instead of 20s of waiting. In the next update this has been fixed so the client checks more often (as intended), meaning it should be closer to that 20s.

Additionally though last week some optimisations were made which halved the processing time and so instead of 20s it'll be closer to 10s (in your case)