With Generate Stitches on (the default), stitches are calculated for new objects whenever you press Enter. They are also updated whenever you scale, transform or move the object. If speed is an issue, you can digitize objects with Generate Stitches off.
To generate stitches for new or selected objects, select Stitch > Generate Stitches or press G.
To remove stitches, or digitize without generating stitches, deselect Stitch > Generate Stitches or press G again.
Tip: Make sure Show Outlines is selected, otherwise stitchless objects will not be visible.