Processing speed is another broad ability factor underlying the g factor (general intelligence).

Definition of Processing Speed (Gs)

Processing speed, a mental efficiency factor, determines the speed of scanning, reading, writing and other well-learned tasks or skills. It is defined as:

The ability to automatically and fluently perform relatively easy or over-learned elementary cognitive tasks, especially when high mental efficiency (attention and focused concentration) is required. Dr. Kevin S. McGrew

Tests of Processing Speed

Perceptual speed. Rate of test taking. Speed of reasoning. Reading speed. Writing speed.

Reference

McGrew, K. S. (2009).  Intelligence 37, 1–10.