The speed of a line- I learned about the speed of the line during one of my first critiques classes at NCSA. It amazed me that it was possible to tell whether a drawn line was made quickly or slowly or with a combination of speeds.
In calligraphy, many factors influence the speed of writing: the pen nib and confidence of the calligrapher, the paper, ink, humidity, the combination of letters, the calligraphy hand, familiarity with the text, etc.
Nibs can be subtlely adjusted to write smoother, to glide more easily. The adjustments are custom made for each calligrapher's touch.
The calligraphers can practice their repertoire of strokes and flourishes to increase speed. And of course, calligraphers can practice speed and accuracy at the same time for any calligraphic hand.
Papers are known for calligraphers gaining great speed or for slowing down calligraphers. Soft papers are known to be slow, while hard papers are usually faster. Textures also count.
Thin Inks are usually faster while thick inks are slower.
Humid days make writing slower and gilding faster!
Words with more minums are faster.
Cursive and joined calligraphy is faster and Black letter and Roman Capitals are slower.
Of course, a memorized text removes hurdles that slow any calligrapher down.
Also, the speed of calligraphy changes within each stroke and that is part of what makes the calligraphic stroke so appealing. A line may start slowly, go full speed and end in a breathtaking whip of a line. The real tour-de-force of a calligraphy connoisseur is to see the speed of the line without seeing the word written. As the Chinese proverb says, "The brush moves again when the character is read." It is also true for pen-made calligraphy.