NAV 2017 Purchase Agent Activities page - slow!

Hi all, I am currently in test with an upgrade to CU4 NAV 2017 and the purchasing role center is extremely slow... Its the Activities page, I have done some SQL profiling on running the page/flowfields and reviewed the keys but to no avail.

Anyone had any problems with this? There are lots of open orders but not enough to cause a speed issue. For a bit of background it is an upgrade from 2009R2.

Any help would be most appreciated!

Thanks.