1. init.sqf
// Remove Gas OFF
_ScriptWait = [0,0,6,3,4,2,1,0,2,1,0,1,0,1] execVM "\her_a3w_survive\scripts\init_her_survive.sqf";

Because the formula of gas removing is ♥♥♥♥♥♥♥♥. For example your vehicle is moving with 60 km/h, the fuel consuption will be:
NewFuelValue = CurrentFuelValue - (speed * 0.01)
at 60 km/h it's 60 * 0.01 = 0.6 per minute!!! It's 60% of your fuel tank per minute at 60 km/h. What a joke.

2.1. Her_Survive.sqf
Her_L_VehicleList = [ <- duplicated string, should be removed
Her_L_VehicleList = [

2.2. Her_Survive.sqf
Her_L_GasList array has wrong format. Currently it is
Her_L_GasList =
[
"Land_wagon_tanker",
"Land_Ind_TankSmall2_EP1",
"Land_Ind_TankSmall2",
// etc
]

MUST BE:
Her_L_GasList =
[
["Land_wagon_tanker" ,0,0,0,6,0,1,1],
["Land_Ind_TankSmall2_EP1" ,0,0,0,6,0,1,1],
["Land_Ind_TankSmall2" ,0,0,0,6,0,1,1],
// etc
]

Wrong array format causes issues with Petrol/Diesel Canister refuelling

3. Uncontrollable unit spawn. It is ez observable using Debug Console and these commands:
hintSilent str (count allUnits);
At the start of the mission there are about 110 spawned units. After 2-4 hours of gayplay there are 200-250 units. Some of units are just not using anywhere, using this script you can mark all units on the map:

// -----------------------------------------------
if (isNil "P_markers") then
{
P_markers = [];
};

{
deleteMarkerLocal _x;
} forEach P_markers;

{
_marker = createMarkerLocal [format ["P_temp_marker_%1", (random 10000)], getPosATL _x];
_marker setMarkerShapeLocal "ICON";
_marker setMarkerSizeLocal [0.5, 0.5];
_marker setMarkerColorLocal "ColorRed";
_marker setMarkerTextLocal format ["%1 (%2)", typeOf _x, damage _x];
_marker setMarkerDirLocal (getDir _x);
_marker setMarkerTypeLocal "mil_arrow_noShadow";
P_markers pushBack _marker;
} forEach allUnits;
// -----------------------------------------------

You can find some units swimming at the [0,0,0] coordinates. Nice gamedesign.

All this crap just eats user's PC performance and FPS doing nothing.