The only safe way to fix NPC run issue I have found is to recreate all original code from TIS. Here it is (copy and past to SuperSurvivor.lua):

function SuperSurvivor:NPCcalculateInjurySpeed(bodypart,b)
local scratchSpeedModifier = bodypart:getScratchSpeedModifier();
local cutSpeedModifier = bodypart:getCutSpeedModifier();
local burnSpeedModifier = bodypart:getBurnSpeedModifier();
local deepWoundSpeedModifier = bodypart:getDeepWoundSpeedModifier();
local n = 0.0;
if ((bodypart:getType() == "Foot_L" or bodypart:getType() == "Foot_R") and (bodypart:getBurnTime() > 5.0 or bodypart:getBiteTime() > 0.0 or bodypart:deepWounded() or bodypart:isSplint() or bodypart:getFractureTime() > 0.0 or bodypart:haveGlass())) then
n = 1.0f
if (bodypart:bandaged()) then
n = 0.7;
end
if (bodypart:getFractureTime() > 0.0) then
n = self:NPCcalcFractureInjurySpeed(bodypart);
end
end
if (bodypart:haveBullet()) then
return 1.0;
end
if (bodypart:getScratchTime() > 2.0 or bodypart:getCutTime() > 5.0 or bodypart:getBurnTime() > 0.0 or bodypart:getDeepWoundTime() > 0.0 or bodypart:isSplint() or bodypart:getFractureTime() > 0.0 or bodypart:getBiteTime() > 0.0) then
n = n + (bodypart:getScratchTime() / scratchSpeedModifier + bodypart:getCutTime() / cutSpeedModifier + bodypart:getBurnTime() / burnSpeedModifier + bodypart:getDeepWoundTime() / deepWoundSpeedModifier) + bodypart:getBiteTime() / 20.0;
if (bodypart:bandaged()) then
n = n / 2.0;
end
if (bodypart:getFractureTime() > 0.0) then
n = self:NPCcalcFractureInjurySpeed(bodypart);
end
end
if (b and bodypart:getPain() > 20.0) then
n = n + bodypart:getPain() / 10.0;
end
return n;
end

function SuperSurvivor:NPCgetFootInjurySpeedModifier()
local b = true;
local n = 0.0;
local n2 = 0.0;
for i = BodyPartType.UpperLeg_L:index(), (BodyPartType.MAX:index() - 1) do
local bodydamage = self.player:getBodyDamage()
local bodypart = bodydamage:getBodyPart(BodyPartType.FromIndex(i));
local calculateInjurySpeed = self:NPCcalculateInjurySpeed(bodypart, false);
if (b) then
n = n + calculateInjurySpeed;
b = false
else
n2 = n2 + calculateInjurySpeed;
b = true
end
end
if (n > n2) then
return -(n + n2);
else
return n + n2;
end
end

function SuperSurvivor:NPCgetrunSpeedModifier()
local NPCrunSpeedModifier = 1.0;
local items = self.player:getWornItems()
for i=0, items:size()-1 do
local item = items:getItemByIndex(i)
if item ~= nil and (item:getCategory() == "Clothing") then
NPCrunSpeedModifier = NPCrunSpeedModifier + (item:getRunSpeedModifier() - 1.0);
end
end
local shoeitem = items:getItem("Shoes");
if not (shoeitem) or (shoeitem:getCondition() == 0) then
NPCrunSpeedModifier = NPCrunSpeedModifier * 0.85;
end
return NPCrunSpeedModifier
end

function SuperSurvivor:NPCgetwalkSpeedModifier()
local NPCwalkSpeedModifier = 1.0;
local items = self.player:getWornItems()
local shoeitem = items:getItem("Shoes");
if not (shoeitem) or (shoeitem:getCondition() == 0) then
NPCwalkSpeedModifier = NPCwalkSpeedModifier * 0.85;
end
return NPCwalkSpeedModifier
end

function SuperSurvivor:NPCcalcRunSpeedModByBag(bag)
return (bag:getScriptItem().runSpeedModifier - 1.0) * (1.0 + bag:getContentsWeight() / bag:getEffectiveCapacity(self.player) / 2.0);
end

function SuperSurvivor:NPCgetfullSpeedMod()
local NPCfullSpeedMod
local NPCbagRunSpeedModifier = 0
if (self.player:getClothingItem_Back() ~= nil) and (instanceof(self.player:getClothingItem_Back(),"InventoryContainer")) then
NPCbagRunSpeedModifier = NPCbagRunSpeedModifier + self:NPCcalcRunSpeedModByBag(self.player:getClothingItem_Back():getItemContainer())
end
if (self.player:getSecondaryHandItem() ~= nil) and (instanceof(self.player:getSecondaryHandItem(),"InventoryContainer")) then
NPCbagRunSpeedModifier = NPCbagRunSpeedModifier + self:NPCcalcRunSpeedModByBag(self.player:getSecondaryHandItem():getItemContainer());
end
if (self.player:getPrimaryHandItem() ~= nil) and (instanceof(self.player:getPrimaryHandItem(),"InventoryContainer")) then
NPCbagRunSpeedModifier = NPCbagRunSpeedModifier + self:NPCcalcRunSpeedModByBag(self.player:getPrimaryHandItem():getItemContainer());
end
NPCfullSpeedMod = self:NPCgetrunSpeedModifier() + (NPCbagRunSpeedModifier - 1.0);
return NPCfullSpeedMod
end

function SuperSurvivor:NPCcalculateWalkSpeed()
local NPCfootInjurySpeedModifier = self:NPCgetFootInjurySpeedModifier();
self.player:setVariable("WalkInjury", NPCfootInjurySpeedModifier);
local NPCcalculateBaseSpeed = self.player:calculateBaseSpeed();
local wmax;
if self:getRunning() == true then
wmax = ((NPCcalculateBaseSpeed - 0.15) * self:NPCgetfullSpeedMod() + self.player:getPerkLevel(Perks.FromString("Sprinting")) / 20.0 - AbsoluteValue(NPCfootInjurySpeedModifier / 1.5));
else
wmax = NPCcalculateBaseSpeed * self:NPCgetwalkSpeedModifier();
end
if (self.player:getSlowFactor() > 0.0) then
wmax = wmax * 0.05;
end
local wmin = math.min(1.0, wmax);
local bodydamage = self.player:getBodyDamage()
if (bodydamage) then
local thermo = bodydamage:getThermoregulator()
end
if (thermo) then
wmin = wmin * thermo:getMovementModifier();
end
--local gametime = getGameTime()
if (self.player:isAiming()) then
self.player:setVariable("StrafeSpeed", math.max(math.min(0.9 + self.player:getPerkLevel(Perks.FromString("Nimble")) / 10.0, 1.5) * math.min(wmin * 2.5, 1.0), 0.6) * 0.8);
end
if (self.player:isInTreesNoBush()) then
local cs = self.player:getCurrentSquare()
if (cs) and cs:HasTree() then
local tree = cs:getTree();
end
if tree then
wmin = wmin * tree:getSlowFactor(self.player);
end
end
self.player:setVariable("WalkSpeed", wmin * 0.8);
end

And in update() function add self:NPCcalculateWalkSpeed() before dovision for example. You can also call this in other places. It need to be tested though, cos I have not tested it well, but it works for random single spawned NPC.