I tend to go too fast around curves, too. Kinda like I drive. lol.
Also, make sure it is not skipping stitches, which makes it look like extra long stitches. Skipping could be from a dull needle, or, in my case, my machine does not like to go in a northeasterly direction. I think it made my needle bend just a bit. I managed to correct this issue by switching to a bigger needle. It leaves needle holes in the top till it is washed, but the stitches are more even.
There are just a lot of things on the machine, and in your actions that have to be "just right" for the stitching to look right.