iRacing in members forum:
One mistake I think we may have made was that we've been testing the track in alpha testing where we already have the graphics optimizations (also in alpha testing). When we discovered the performance difference without the optimizations we attempted some last minute track optimizations. There will be more to come...

It is also true that with high end GPU's, Spa and RA are CPU bottlenecked. We've been focusing on that in the changes actually. With 3 monitors at roadamerica and render per view on, my fps has increased from 57 to 102 at a bad spot (in alpha testing compared to members). Pretty much 20% everywhere around tracks like RA and Spa minimum, up to much more - it just wasn't ready for this release.

It's possible some spa specific fixes may be released within a couple weeks. I suspect that major engine optimizations will be released next season, end of Jan? I know they will help somewhat at these worst tracks. I might do some comparisons and post a few later. Every PC is different, its not like a PS3 where its all the same for everyone

OK. I did a quick test.

On members, the worst spot at spa with 3-screens and render-per-view is 35 fps for me. The same spot on alpha testing is 57 fps for me. So that's a 62% increase? Its not like that at all tracks, but at spa and ra, with three screens, it is like that. Some hope is on the way I guess.

Also, we need to speed up the track itself, it is a pig.