Pen Lifts are often referred to but not always understood. Advocates of conventional cursive cite the advantages of writing whole words without lifting the pen. Truth to tell, many who were brought up with, and continue to write a good conventional cursive hand let their pen drift off the page between letters. The word is drift, not lift, a light, not heavy lift.
Move a pencil through a print-script alphabet and there are many lifts between, and even within letters. Mention cursive italic to one who supports conventional cursive instruction in the schools, and the response notes lifts between letters within words. The myth is that the lifts are similar to those made for print-script, therefore it stands to reason that cursive italic slow. NO!: the movement is drift, not lift. Some cursive italic letters appear separate on their page, but the pen moves fluently; it scarcely leaves the paper. It drifts.
Studies have shown cursive italic to be faster, but solid research remains on the shelf. My bet is on italic as the winner in both speed and legibility.