NAV 2015 Performance issue, Not SQL, rather ASync I/O

I.e. the SQL server is trying to push data on the NAV Server and has to wait for the NAV Server. Measured by the IT team but also on a user experience level, you feel a 2 sec latency at every query regardless of whether it is 1 record or 10000.

At CU4, will moving to CU28 help? Since it means database conversion and likely having to stop operations for half a day I am a bit vary of it, would only do it if it seems likely it will help.