Hola, i have got a pathfinding problem please help? (Read description)

the problem is that is that the killer is supposed to be fast and he is at far distance but as sonn as he gets close to a player hes just as slow as the player adn wont be able to catch up and kill u. please help im so confused

here is the code: i know its long tho. Sorry

local SearchDistance = 300

local ZombieDamage =    100     
local DamageWait =      0

local WanderX, WanderZ = 30, 30





function getHumanoid(model)
    for _, v in pairs(model:GetChildren())do
        if v:IsA'Humanoid' then
            return v
        end
    end
end


local zombie = script.Parent
local human = getHumanoid(zombie)
local hroot = zombie.Torso
local zspeed = hroot.Velocity.magnitude
local head = zombie:FindFirstChild'Head'
local vars = script.vars

local pfs = game:GetService("PathfindingService")
local players = game:GetService('Players')

-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

local path
local waypoint

local chaseName = nil

function GetTorso(part)
    local chars = game.Workspace:GetChildren()
    local chaseRoot = nil
    local chaseTorso = nil
    local chasePlr = nil
    local chaseHuman = nil
    local mag = SearchDistance
    for i = 1, #chars do
        chasePlr = chars[i]
        if chasePlr:IsA'Model' and chasePlr ~= zombie then
            chaseHuman = getHumanoid(chasePlr)
            chaseRoot = chasePlr:FindFirstChild'HumanoidRootPart'
            if chaseRoot ~= nil and chaseHuman ~= nil and chaseHuman.Health > 0 and chaseHuman.Name ~= "Zombie" then
                if (chaseRoot.Position - part).magnitude < mag then
                    chaseName = chasePlr.Name
                    chaseTorso = chaseRoot
                    mag = (chaseRoot.Position - part).magnitude
                end
            end
        end
    end
    return chaseTorso
end

function GetPlayersBodyParts(t)
    local torso = t
    if torso then
        local figure = torso.Parent
        for _, v in pairs(figure:GetChildren())do
            if v:IsA'Part' then
                return v.Name
            end
        end
    else
        return "HumanoidRootPart"
    end
end

-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

local damagetime
local damagedb = false

for _, zambieparts in pairs(zombie:GetChildren())do
    if zambieparts:IsA'Part' and human.Health > 0 then
        zambieparts.Touched:connect(function(p)
            if p.Parent.Name == chaseName and p.Parent.Name ~= zombie.Name and not damagedb then 
                damagedb = true
                damagetime = time()
                local enemy = p.Parent
                local enemyhuman = getHumanoid(enemy)
                vars.Attacking.Value = true
                enemyhuman:TakeDamage(ZombieDamage)
                vars.Attacking.Value = false
                while wait() do
                    if damagetime ~= nil and time() >= (damagetime + DamageWait) then
                        damagedb = false
                        damagetime = nil
                    end
                end
            end
        end)
    end
end


spawn(function()
    while vars.Wandering.Value == false and human.Health > 0 do 
        vars.Chasing.Value = false  
        vars.Wandering.Value = true
        local desgx, desgz = hroot.Position.x+math.random(-WanderX,WanderX), hroot.Position.z+math.random(-WanderZ,WanderZ)
        local function checkw(t)
            local ci = 3
            if ci > #t then
                ci = 3
            end
            if t[ci] == nil and ci < #t then
                repeat ci = ci + 1 wait() until t[ci] ~= nil
                return Vector3.new(1,0,0) + t[ci]
            else
                ci = 3
                return t[ci]
            end
        end

        path = pfs:FindPathAsync(hroot.Position, Vector3.new(desgx, 0, desgz))
        waypoint = path:GetWaypoints()
        local connection;

        local direct = Vector3.FromNormalId(Enum.NormalId.Front)
        local ncf = hroot.CFrame * CFrame.new(direct)
        direct = ncf.p.unit
        local rootr = Ray.new(hroot.Position, direct)
        local phit, ppos = game.Workspace:FindPartOnRay(rootr, hroot)

        if path and waypoint or checkw(waypoint) then
            if checkw(waypoint) ~= nil and checkw(waypoint).Action == Enum.PathWaypointAction.Walk then
                human:MoveTo( checkw(waypoint).Position )
                human.Jump = false
            end

            if checkw(waypoint) ~= nil and checkw(waypoint).Action == Enum.PathWaypointAction.Jump then
                connection = human.Changed:connect(function()
                    human.Jump = true
                end)
                human:MoveTo( waypoint[4].Position )
            else
                human.Jump = false
            end

            if connection then
                connection:Disconnect()
            end

        else
            for i = 3, #waypoint do
                human:MoveTo( waypoint[i].Position )    
            end
        end
        wait(math.random(4,6))
        vars.Wandering.Value = false
    end
end)

-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

while wait() do
    local nrstt = GetTorso(hroot.Position)
    if nrstt ~= nil and human.Health > 0 then 
        vars.Wandering.Value = false
        vars.Chasing.Value = true
        local function checkw(t)
            local ci = 3
            if ci > #t then
                ci = 3
            end
            if t[ci] == nil and ci < #t then
                repeat ci = ci + 1 wait() until t[ci] ~= nil
                return Vector3.new(1,0,0) + t[ci]
            else
                ci = 3
                return t[ci]
            end
        end

        path = pfs:FindPathAsync(hroot.Position, nrstt.Position)
        waypoint = path:GetWaypoints()
        local connection;

        local direct = Vector3.FromNormalId(Enum.NormalId.Front)
        local ncf = hroot.CFrame * CFrame.new(direct)
        direct = ncf.p.unit
        local rootr = Ray.new(hroot.Position, direct)
        local phit, ppos = game.Workspace:FindPartOnRay(rootr, hroot)

        if path and waypoint or checkw(waypoint) then
            if checkw(waypoint) ~= nil and checkw(waypoint).Action == Enum.PathWaypointAction.Walk then
                human:MoveTo( checkw(waypoint).Position )
                human.Jump = false
            end

            if checkw(waypoint) ~= nil and checkw(waypoint).Action == Enum.PathWaypointAction.Jump then
                connection = human.Changed:connect(function()
                    human.Jump = true
                end)
                human:MoveTo( waypoint[4].Position )
            else
                human.Jump = false
            end

            hroot.Touched:connect(function(p)
                local bodypartnames = GetPlayersBodyParts(nrstt)
                if p:IsA'Part' and not p.Name == bodypartnames and phit and phit.Name ~= bodypartnames and phit:IsA'Part' and rootr:Distance(phit.Position) < 5 then
                    connection = human.Changed:connect(function()
                        human.Jump = true
                    end)
                else
                    human.Jump = false
                end
            end)

            if connection then
                connection:Disconnect()
            end

        else
            for i = 3, #waypoint do
                human:MoveTo( waypoint[i].Position )    
            end
        end
        path = nil
        waypoint = nil
    elseif nrstt == nil then 
        vars.Wandering.Value = false
        vars.Chasing.Value = false
        CchaseName = nil
        path = nil
        waypoint = nil
        human.MoveToFinished:Wait()
    end
end