Hey Watson,
I have the HQ Sweet Sixteen ( same as your Tiara) and like you I don't have the stitch regulator (I tried one and didn't like it at all). When I'm doing ruler work I can be anywhere from 12 to 20 percent on my speed. I tend to go a little faster if I'm doing large scale FMQ -- maybe around 30-40 but if I'm doing any micro quilting FMQ fills then I'm usually between 20 and 30. So, no, you're not the only one who goes slow.
I think what Helen Godden is talking about is folks who are having trouble with tension around curves and direction changes or when they're trying to do smooth curves and instead are getting jagged curves, or are having problems getting good consistent stitch sizes. Folks who are having those kinds of problems may be able to fix them by speeding up their machines. But I'd say if you're happy with your stitch size, consistency and tension then you're doing it the right way for you.
Rob