I am rendering to a texture, I am rendering many intances of a vertice that will have different locations in the texture I am going to render to, but then what happens when more than 1 vertice points to the same pixel of a texture, and I have blend enabled, does it loses all the pixel shader parallel performance?
performance question
Not really, since which ever vertex gets interpolated second will have to run after the other pixels in order to blend properly and can't really run in parallel.
I am rendering to a texture, I am rendering many intances of a vertice that will have different locations in the texture I am going to render to, but then what happens when more than 1 vertice points to the same pixel of a texture, and I have blend enabled, does it loses all the pixel shader parallel performance?
No, not really. Since there are many shader units, the pixels can be processed in parallel, then passed on to the output merger where they are blended. This is more or less the same situation as when the pixels aren't overlapping - the OM has to serialize the writing to a particular portion of the render target.