How many particles is TP generating? Do you get this same behaviour if you try to generate a single particle? You might try to render the same scene in Default Scanline with facing geometry or something to see if it is much faster.
How many particles is TP generating? Do you get this same behaviour if you try to generate a single particle? You might try to render the same scene in Default Scanline with facing geometry or something to see if it is much faster.