But to be fair, plain Jira can be pretty fast, it’s just when you get into an enterprise environment and people think they need 2000 different fields things fall apart.
Caching works for 99.9% of cases, 'but sometimes', I click on an issue and it was just updated just before my page rendered.
We don't use much stuff and it's a bit older version 7.8, but I cannot complain so far.
Load times are atrocious. It's the slowest website I have ever seen. Maybe facebook is slower, but I don't use that as often.