My understanding is that JIRA was originally built as an on-premises solution, so request latency wasn't an issue.
Then they moved everything to a cloud hosted solution, but the assumption of requests being effectively zero latency was still built-in, so now firing hundreds of requests with high latency makes everything feel super sluggish.
I'm working on my own issue tracker [0] that stores everything locally, which means no network latency. Eventually I'd like to build a sync backend for it so you can share it with a team, but for now everything runs locally.
Yeah, our on-prem Atlassian installation is utter crap performance wise, opening a Confluence page often takes 30 seconds or more. I also get pissed off every time we try to upgrade our SolidWorks installation because they share a DB server. Atlassian doesn't support the most recent versions of Microsoft SQL Server, but SolidWorks only supports the latest couple revisions of Microsoft SQL Server so every time it is a pain to ensure that both systems are compatible and my IT refuses to move SolidWorks to a new server.
The cloud is the original code base and the on premise is a FORK! Can you believe it? It's not even the same code and the on premise solution is so far behind.
My rage builds even just trying to use the search bar on JIRA. Keys don't get captured and get registered as page hot keys, or some keys are registered and others aren't. Crazy, just give me a dumb static search bar if you're not going to make life better. /Rant