The Pages administration functions (move, view, add) are extremely slow after upgrading from 4.9 to 5.2.  The control panel links seem ok but the Admin -> Pages functions are extremely slow.  The rest of the site seems to be performing well.   A potential factor is the site has over 1200 pages and counting.  We are looking at moving the bulk of these into a module but the recent slowdown is affecting maintenance now.  This wasn’t an issue on 4.9 but perhaps how tabs are moved and manipulated has changed in 5.2? 

Is there anything else I should be looking at?

I hadn't touched the cache settings for the page but the site was on heavy then light and cleared numerous times.  I have subsequently played with the cache settings on Admin/pages now to no avail. 

Every single admin function on the page including view takes well over a minute and a half to complete.  Other sections feel responsive.

can you identify, whether performance is affected by web server or sql server?