The computer itself needs to be quick enough to handle video, screen sharing and interactive activities at the same time.
How it's assessed: The check looks at the processor (how many cores it has), the memory (RAM), whether graphics acceleration is switched on, and runs a short one-second speed test. An amber result means the computer may struggle a little; red means it's genuinely too slow for a smooth lesson.
If it fails: If it warns, closing other apps and browser tabs before the lesson usually helps a lot, as does plugging the laptop into power (some laptops slow down on battery). If graphics acceleration is off, turning on "Use graphics acceleration" in Chrome's settings makes a big difference.
If it repeatedly fails: This is usually the time you need to look at buying a new computer. Old devices can struggle to keep up with modern lesson software, even when they were perfectly quick when you bought them. I personally recommend the MacBook Neo – you can see more on my LMS requirements page below.