Just the one terrain to try it, resources at start show 87% which is about normal, I switched the messages off anyway, always do [LOL], after populating the std terrain, resources dropped to.......wait for it.....86% so I don't think that's an issue there, after ticking the full quality box, the resources stayed at 86%....I would expect nothing less, I do have 8 Gig to play with!
It's gone real slow again now, bordering on crawling, resources still show 86%, poly count is 469,819,700
It's slowed to a crawl again now!!!.......really puzzling!

By way of comparison, the windy hill eco comes in at 4,968,804 polys with resource at 86% and no slow down.
The problem does seem to be associated with the pastures ecosystem!

Injustice will be avenged.
Cofiwch Dryweryn.