How to stop lag from my procedural generation script?

I've been trying to make procedural terrain based off of Roblox's example on the developer hub. However, I get major lag spikes when the character moves. My code is the following:

EDIT: On further inspection, it seems to not work past the render distance of the player. Meaning, it will generate 2 chunks around the player at the start (the render distance), then not generate anything else at all.

local CHUNK_SIZE = 64
local RENDER_DISTANCE = CHUNK_SIZE * 2 
local CHUNK_MAX_HEIGHT = 0

local function chunkExists(chunkX, chunkZ)
	if not chunks[chunkX] then
		chunks[chunkX] = {}
	end

	return chunks[chunkX][chunkZ]
end

function checkSurroundings(location)
	local range = math.max(1, RENDER_DISTANCE)
	
	for x = location.X - range, location.X + range do
		for z = location.Z - range, location.Z + range do
			local checkingPoint = Vector3.new(math.floor((location.X / 4) + x), 0, math.floor((location.Z / 4) + z))
			local chunkX, chunkY, chunkZ = round(checkingPoint.X), CHUNK_MAX_HEIGHT, round(checkingPoint.Z)
			
			print(chunkX, chunkZ)
			local cx = chunkX
			local cy = CHUNK_MAX_HEIGHT
			local cz = chunkZ
			if not chunkExists(cx, cz) then
					
				--IRRELEVANT CODE
					
				makeChunk(cx, cy, cz)
			end
		end
	end
	
end

game.Players.PlayerAdded:Connect(function(player)
	local db = false
	player.CharacterAdded:Connect(function()
		local char = player.Character
		local hrp = char:WaitForChild("HumanoidRootPart")
		local pos = hrp.Position
		hrp:GetPropertyChangedSignal("Position"):Connect(function()
			if pos.X ~= hrp.Position.X or pos.Z ~= hrp.Position.Z then
				if db == false then
					checkSurroundings(hrp.Position)
					pos = hrp.Position
					db = true
					wait(1)
					db = false
				end
			end
		end)
	end)
end)

Note: Some code has been removed to keep the script relevant