Quilting, for me at least, is straight line which I use the walking foot and go as fast as I can and still keep straight lines. Or it is FMQ, which is usually done following a pattern drawn on the quilt, so I move the quilt slower and keep the machine stitching slower, which gives me a better result. I have a 6600 and have found that using a larger needle (16/18) and poly thread works the best for FMQ....at least for me. I agree on finding a more stable surface to eliminate vibration.