The early days of Pixar were technology people like Ed Catmull and Alvy Ray Smith, who really wanted to make movies with computers but didn't have the artistic skill themselves. So they brought on people like John Lasseter, who had the animation skill and experience.
Aaron Hertzmann, Aaron Hertzmann on Caring about People
When Pixar would render a movie, it'd take 24 hours for one frame—and 30 frames a second. These things used wild amounts of power.