Jira's main problem is that for most developers, this enormous piece of enterprise software is strictly inferior to a swimlane app they could build in a week. Lots of features in there for the benefit of managers and PMs that ultimately amount to more administrative work and process for developers.

Some places it's bad enough that Jira is used to appease the people with the purse strings, and the inputs have no bearing on reality at any given moment, while all the real workflows are tracked using paper note cards pinned to a cork posterboard that sits on Joe's desk behind his monitors.

Jira's slowness became worse and worse in the past ~5 years. I used to remember the Jira hate and not understanding it because it indeed got a bad rap because people blamed Jira for a shitty PM process - with a proper process, Jira itself wasn't bad and I enjoyed using it.

However the last few times I've used it, it wasn't the PM process that sucked - in fact I loved my PMs because I got to offload most of the Jira upkeep to them and never touch the tool myself. However every time I have to use the pile of shit myself I end up mumbling quite colorful language.

Get stuck using Mercury, err, HP, umm, I mean Micro Focus Quality Center for 15+ years and JIRA will feel like a breath of fresh air.