backburner split scan lines overlap

Why can't I get backburner to render the strip height that I specify? If I 
want sixty 8 pixel strips with 0 (zero) overlap, I get 32 pixel overlapping 
strips. This means it is taking 4 times longer to render than it should. How 
do I prevent this. Thanks it advance.

The overlap is necessary to calculate the antialising. So the bigger the 
aa-area is defined, e.g. 25-pixel blurr filter, the bigger the overlap will be.

The minimum of 6 lines overlapp in each direction can never be avoided 
(that´s what some test have revealed). Try this: Split an image into 8px high 
segments with and without aa activated and compare the height of the 
resulting segments.