Thanks for the reply Laurel. I spent quite a bit of time last week reviewing my model and trying your suggestions. Certainly helped - had something that I could work with by the end even if a bit slow but certainly workable :-)
Thanks for your reply and explanations
PPS: I should add I have tried changing the monitor to 640by480 with no impact whatsoever (I used a stopwatch on my phone and same to the nearest second). I have also unchecked all items in the special effects and other special items in "Set view options"
I have used ETABS in the past to build small (40m by 40m) but detailed models. It has all worked acceptably. Today I have built a large scale model (200m by 400m). It has no detail however (ground and then two curved triangular floors (beams around outside with slab and diaphragm). The grid is...