Deleting items by batches very slow

Hi!

I have a large list and trying to remove items by batches with c# code like this

http://sharepoint.stackexchange.com/questions/39579/fastest-way-to-delete-all-items-with-c

I just set query.Rowlimit = 2000 instead 100.

So, deleting is very very slow! It takes around 20 minites to delete 2000 items.  

May be RowLimit attribute should be less then 2000?It plays an important role here? please, help!