Hi Makigirl!
Thanks for the advice. I did have on-screen msg turned on but choose to ignore them since too many issues at hand. Set poolsize to 5000MB now and its somewhat better I think.
Regarding the face snap issue, I deleted most overlaying faces from relevant assets ( so the mouldings have no backside for example and just a thin front face ) and reimport and build them. It look definitely better than before but the issue still exist
I think the main problems are, these outlines appear darker & thicker as the viewing distance ( object to pawn ) increase. And these assets, including mouldings on furniture in particular, look generally fine from a 1-2 meter distances. Screenshot enclosed below:
The screenie door would look fine ( mostly ) when the pawn stay close. when its zoomed out, about 3 meters and beyond, these lines start to appear and they mostly concentrate in and around the mouldings. Another aspect of this is, if you quickly zoom out from a close view when the object in perfect status, the dark lines wont appear until pawn is 5-6 meters away. So quickly zooming out from close to afar seems to alleviate the problem more or less.
And if quickly pan the camera from a close-up view to another section of the map, these lines became really heavy ( entrance door angle view . quick pan-zoom ) as compared with a normal, more slowly pan would render ( entrance door angle view . normal ), as if the engine doesnt have enough time to render out the scene when the camera is panned quickly.
So maybe this issue is distance related? or have something to do with how the engine re-draw or render the same object for different vewing distance? is there settings that could at least reduce the issue somewhat if not complete eliminate them, since most of the object LOOK FINE when looking at close distance.