OK, so I think I figured out what the cause of this is, but do not understand why it would do so.
See attached: Wire frame renders
The 1st plate is what I had. 12 dinner and 12 side plate plus 1 large centre plate per table.
The plate has 4 edges filleted and my guess is, that is where the problem lies.
The 2nd plate is what I recreated as you can not edit a filleted object the same way as you can with extrudes.
It has no fillet, just the solid subtraction.
When it renders it is much more smoother and when viewing the table in a 3d view it loads almost instantly, unlike the 1st plate where it took awhile to generate each table.
Is this a problem for VW to render all these filleted areas?
If so Why?
Will do Render later and see how it copes...