You can get counts with:
http://www.google.com/reader/api/0/stream/items/count?s=user/-/state/com.google/starred
If you want a bit more data, you can get starred item IDs and
timestamps with
http://www.google.com/reader/api/0/stream/items/ids?s=user/-/state/com.google/starred&n=10000.
That should return much faster than actually getting feed contents.
Mihai
Does `all=true` have any effect? I tried including and omitting but couldn't see a difference.