Seems this thread had been invaded by Microsoft.
as clearly TFS is thge big stinking turd here, that is desperately trying to play catchup to JIRA and only needs another 5 years to get there.
a properly setup and configured JIRA with workflows that suit your company is a really good product, and the Agile and Kanban boards work really well. If you have suffered TFS and JIRA, you will know how far behind TFS is.
I'm also surprised the Microsoft shills brought up performance, we host ours on a very modest server spec, with no performance issues whatsoever, and it's loaded up with plenty of add-ons for time-sheet management, portfolio planning, and application links to source and build servers. We have 100% uptime, it only needs rebooting when installing updates, which we do frequently, and never have upgrade problems, they are totally painless.
If someone genuinely does have issues with JIRA, it likely more reflects on your admin doing a really bad job of configuring it, and it's workflows, than the product itself