I am attaching another test that demonstrates that the speed of the turtle is different when it draws a straight line and a circle.

The output shows the time it takes to draw a line and a circle of the same length at various speed settings.

$ python3 speed_test2.py
         0: 0.01 0.02
         1: 0.96 2.25
         2: 0.67 2.24
         3: 0.32 1.81
         4: 0.25 1.39
         5: 0.27 1.89
         6: 0.15 1.44
         7: 0.12 1.53
         8: 0.10 1.69
         9: 0.10 1.73
        10: 0.08 1.64