There are a few reports there of games on Unreal Engine 3 having graphical glitches and performance issues under 8.3. It looks like Unreal Engine 3 is not getting updates anymore[0], so it's possible that UE3 users are stuck. (I don't know if Spiderweb use UE3).
I would be very, very surprised if they were using UE3, considering their games haven't seen much of a graphical update since... 1994? Really old school in literally every single way. Think Ultima Online, then take a step back from that.
However, I wouldn't be surprised if they suffered from a similar regression.
However, I wouldn't be surprised if they suffered from a similar regression.