About how fast is fast enough for a web application?

About how fast is fast enough for a web application? Here’s a quick overview of key performance metrics:

1. Under 100 milliseconds is perceived as instantaneous
2. A 100 ms to 300 ms delay is perceptible
3. One second is about the limit for the user's flow of thought to stay uninterrupted
4. Users expect a site to load in 2 seconds
5. After 3 seconds, 40% of visitors will abandon your site
6. 10 seconds is about the limit for keeping the user's attention

Excerpt:

https://techbeacon.com/web-performance-testing-top-12-free-open-source-tools-consider