Animations look fine in editor but become jerky when played?

My animations are smooth when I play them in the animation editor, but when played in-game, they look weird and choppy. I've looked at others describing the same issues, but the solutions either don't work for me (such as animation weights and priorities) or are outdated.

Video of both editor and in-game animation: https://streamable.com/d9dqr7

Code used to play counterattack animation (local script):

local UserInputService = game:GetService("UserInputService")
local player = game.Players.LocalPlayer
local character = player.Character or player.CharacterAdded:Wait()
local debounce = false
local ReplicatedStorage = game:GetService("ReplicatedStorage")
local swordDamage = ReplicatedStorage.SwordDamageRemoteFunction
local beingUsed = ReplicatedStorage.BeingUsedRemoteFunction
local CurrentAction = script.Parent.Parent.CurrentAction.Value

--[[local AudioPlayerModule = require(ReplicatedStorage:WaitForChild("AudioPlayer")
AudioPlayerModule.preloadaudio({

})]]

--[[
11768323667 right
11768327293 up
11768331665 left
]]

repeat wait() until character.Humanoid
local humanoid = character.Humanoid
local anim = Instance.new("Animation")
anim.Parent = humanoid
anim.AnimationId = "https://www.roblox.com/asset/?id=11762237171"--11749156719
local playAnim = humanoid:LoadAnimation(anim)

UserInputService.InputBegan:Connect(function(Input , IsTyping)
    if not IsTyping and not debounce and Input.UserInputType == Enum.UserInputType.MouseButton1 then
        debounce = true
        wait(0.1)
        playAnim:Play(0, 1, 1)
        CurrentAction = "Slice"
        swordDamage:InvokeServer(character.SliceDamage.Value, true, 0.5, true)
        --sound goes here
        --AudioPlayerModule.playAudio("")
    end
    local seconds = 0
    repeat seconds += 0.1 wait (0.1) until seconds >= 2 or CurrentAction ~= "Slice"
    playAnim:Stop()
    swordDamage:InvokeServer(0, false, false, false)
    beingUsed:InvokeServer()
    if seconds >= 2 then
        CurrentAction = nil
    end
    debounce = false
end)

Code used for idle animation (local script):

local tool = script.Parent
local anim = Instance.new("Animation")
anim.AnimationId = "http://www.roblox.com/Asset?ID=11749602892"
local track
tool.Equipped:Connect(function()
    track = script.Parent.Parent.Humanoid:LoadAnimation(anim)
    track.Priority = Enum.AnimationPriority.Action
    track.Looped = true
    track:Play()
end)
tool.Unequipped:Connect(function()
    if track then
        track:Stop()
    end
end)