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In the BG1 NPC Project readme, it is written that the "walking speed fix" included in tutufix introduces some issues with spells such as haste or polymorph. Do you know if it is still the case as of version v18 ?
I think polymorph, haste, and slow still misbehave.

I prefer tutu, and never used the walking speeds tweak. The only components I ever used with Tutufix were "balanced totemic summons" and "ammo stacks like BG2".

G3 has a beta walking speeds in their tweak pack, you might want to check that out to see if they've made progress. They may have just adapted the code from tutufix, idk.