Well that is not exactly what I was thinking about. but it does provide some data. with the tuning word = 1 I caculate it takes about 24 instrcution cycles to get through the main loop. thats 3 uS. or the 333K you referenced above. IMHO that seems plenty fast enough to make a 5K signal. at 5K, you will have enough time to run your loop ~66 times. so thats 33 loops for each half cycle. so every 5.4 degrees you change output values. that would be the same as skipping values in the table I suppose. I know I am not helping here, but something just feels better thinking about the values this way. the next issue is sine waves are not triangle waves. there is more action over time at the reversals. during the rise and fall they are almost vertical, well more then 45deg anyway. So it seems to me you need more of those samples there.