This basic shape prints very fast, It helps test how retraction setting is working. In the attached picture can be seen at left a retraction of 4 mm, what performs good. In the right side of the picture, a second one with retraction set to 1.8, causing hairs to appear as printing head moves from one leaf to the other.

Retraction value is a measure in mm that is to be adjusted in order to make your printer retract filament before moving to a diferent position. Too much retraction causes bubles as air gets inside printing head. Too few causes hairs.

Regards,