I just reintalled Assetto Corsa on my machine (GTX1050, old i7-2600, 16GB RAM, 1920x1080) just to make sure where all these problems come from.
- With a new and stock AC installation and only Goodwood FoS v0.91 track files I get CTD when I try to load the track in practice mode.
- installing stFlow_1.0 and the track loads fine without any stuttering issues - Video Walls working, Plane works
- installing Content Manager
- installing CSP 49 - track loads fine without any stuttering issues - video walls working, plane working
- switch to CSP 129 - track loads fine without any stuttering issues - video walls working, plane still not working
- installing SOL 1.2 - track loads fine without any stuttering issues - video walls working, plane still not working
- switch to CSP 74 - track loads fine without any stuttering issues - video walls working, plane working
Conclusion: I don't know!