Guidelines for the Human Perception of Speed

Posted on July 27, 2015

It’s important to remember that measured performance and perceived performance do not always align. The brain is a strange organ that has a habit of distorting the reality around us.

In his book High Performance Browser Networking, Ilya Grigorik sets out some guidelines for the humans’ perception of speed. Keep these in mind when performance testing your websites.

  • 0”“100ms - Instant
  • 100”“300ms - Small perceptible delay
  • 300”“1000ms - Machine is working
  • 1000+ms - Likely mental context switch
  • 10,000+ms - Task is abandoned