I didn't interpret the OP to mean slow from an "application performance" perspective - instead, as slow from a "process" perspective.
The ticket needs to be filed in the right queue. It needs the "right" tags. It needs to traverse the "approved" workflow correctly. It didn't get assigned to the right epic. etc, etc, etc.
It's all of that - the process built up over time, in response to organic needs - that makes things "slow" and drives such a rejection of these tools by developers and their teams. We (collectively) rarely step back and say "what process can we cut?" - only when we use a new tool do we have the chance to address that.
It's both. JIRA can often be terribly slow. Each page loads about 10 seconds for me, and I don't know why. Other people say it is ~2s for them. I suspect it has something to do with networking and amount of requests being made, etc.
Then, on top of it the flows in Jira can be super slow, which is another story.
The ticket needs to be filed in the right queue. It needs the "right" tags. It needs to traverse the "approved" workflow correctly. It didn't get assigned to the right epic. etc, etc, etc.
It's all of that - the process built up over time, in response to organic needs - that makes things "slow" and drives such a rejection of these tools by developers and their teams. We (collectively) rarely step back and say "what process can we cut?" - only when we use a new tool do we have the chance to address that.