My guess is that it might have to do with the fact that if N is large enough, doing it in chunks lets the graphics card draw while you''re filling in the next chunk. But then the snag comes in when there aren''t that many vertices and you''re locking and unlocking the VB, which is overhead.

Another thing might be that it just saves memory if you do it in chunks.

Whatever the original reason might be, it''s just become a rule-of-thumb. But if the way you''re doing is working faster for your game (on yours and other test machines) then by all means keep it.


TLC

I would have said that using a dynamic buffer and filling it a chunk at a time is faster because if you have a buffer 65536 large, clearing it every frame would be slow...
The D3D pointsprites demo fills up with about 512 points ( I think, off the top of my head) then renders what it has so far. It then continues until all the particles waiting to be rendered are actually rendered. If the buffer is full, it renders what it has added, clears the buffer, then continues.
To get this to work, tho, you have to set the buffer flags up correctly or it will be very slow. Knowing how to set up, fill and render it efficiently is the key to speed here.