May you please provide us with more details on the expected and observed behaviour? What makes you feel that the update sequence is unnatural?
Note that if your application sends 2-3 kb fields and there are as many as 256 fields in an item and the fields change frequently, then the bottleneck might be on the client side as well.
Are those fields images that the client renders on the screen?
If the different fields are not meant to be updated by the client at the same time, you could rather try to define 256 items with one field each and see if the final effect is better.