Well, Daggerfall Unity itself is relatively lightweight (not as lightweight as classic game, but like an average-to-modest 2016-ish 3D game), it's the selection of mods from the GOG Cut that drastically increases hardware requirements (CPU, GPU and memory).
So I'd say, try experimenting by disabling all mods. If that's not sufficient, you can reduce Terrain Distance (Video / Advanced / Terrain Distance), switch to simplified interior lighting (Video / Advanced / Ambient Lit Interiors), or use one of the retro resolutions (Esc in game to display options menu / Chevron at the very top left of screen / Effect Settings / Retro Mode / Mode)
https://forums.dfworkshop.net/viewtopic.php?p=20105#p20105 If performance is good enough, you can consider re-enabling mods that you find interesting. Gameplay-only mods are the most likely to have little impact on performance.
PS: If you do not re-enable texture mods but go with classic textures instead, I recommend you set main filter (Video / Main Filter) to "Point" so classic pixel art stays crisp and not turned into pixel porridge.
