I’d try the new engine.
I know for the majority of people it’s not working, but I’ve got this…
…and it can’t or the life of it seem to run its MX940 with the old engine properly. The frame rates are below 20fps with the old engine, and while it’s pretty clear the new engine has some issues with the Nvidia card, instead of 20fps in Old Athen with the old engine I get 30-40 fps in Old Athen with the new engine. Maybe a bit more, because the old engine seems a bit like trying to dance in treacle on the old engine.
That said, the new engine will, for me, crash occasionally wherever there are whompa effects/textures to load.
It also loads pretty spiffily. I’ll sometimes in cities and SL temples watch walls and items load into existence after zoning while I’m happily running around (this is probably more down to having single channel RAM due to waiting out memory pricing/not really caring much.)
This is also what my options look like after mucking about with @Caloss2’s suggested Nvidia shenanigans. I can assure you, it’s my dedicated card working with these settings. It gets agitated, hot and bothered.