You are the first person I ever read making complains about the circular needles. Usually the circulars are much easier on your hands than the straight ones. Maybe the circular needles you used for the shawl were a little bit too short, so you needed to force the stitches to stay in place? It happened to me when I was much younger and did not have circular needles in different lengths. I guess that can contribute to the stress. Also the repeating movements. I like the Mediterranean style (you call it Portuguese just because some girl from Portugal made the first video on youtube), but I find it about 2 times slower than the continental style. As one of my grand-aunties used to teach me - "The way this one of my sisters knits is awfully wrong (she was using the over the neck method), and the way the other one knits is too slow (the other aunt went in some kind of missionary middle to high school, and the English ladies forced her to knit English style). " And knowing that these ladies went through some very hard times during the wars in Europe, when only the knitting to the market helped them to survive ...