Zephyr on Jira Datacenter is very slow

Hello, I've got very strange problem. First of all, there is no load at server, like 0.02 load average. But simple operations like move test case from one folder to another or creating new folder are very slow, no errors at logs (or I cant find it), just after few minutes (or hour) new folder appears or test case moves to the right place. 

I've googled a bit, and disabled every debug logs, rebuilt index, checked database queue. Everything looks fine. Now I need some advice or help about this.