Gydion: I don't go in much for random, blind guessing. If you can bother yourself to state your basic system info, Wine version used, Wine package installed from, and any other relevant information that would be great. Then I might try some possibly informed guessing.
How often and when was the last time you updated Wine?
As for sys info - Im using the MSI GE60-2PC laptop:
i7 4700HQ as CPU
Intel HD graphics 4600 / Nvidia 850M (via bumblebee, coz didnt find any other working solution) as GPU
8Gb ram
As for wine version: it used to be 3.13 (I've stated that above, I think).
As for installation source - distro's repo (manjaro).
Update wine as much, as distro itself - in about a week after initial release of each new version.
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Unrelated to New Vegas:
Atleast on my setup,
flatout 2 has regression on wine 3.14 (after 3.13 and below) - issues with sound mixing, which leads to weird noises and effects, similar to "sound from under water". Disabling winegstreamer and csmt didnt do anything, if thats matter. Used pulsa as default sound output