Efficiency in checking for position / magnitude?

So I'm trying to make a basic NPC-like dialog GUI appear when a player walks near a certain part. Only problem is, I feel as if my code is somewhat inefficient. I use a while loop and magnitude to compare the player's torso position, to the target part. Here's a brief example of what it looks like:

-- Services
local players = game:GetService("Players")

-- Client
local client = players.LocalPlayer
local mouse = client:GetMouse()
local char = client.Character or client.CharacterAdded:wait()
local torso = char:WaitForChild("Torso")

-- Workspace
local npc = workspace:WaitForChild("NpcPart")

-- Main loop
while wait(1) do
	if (torso.Position  - npc.Position).Magnitude < 10 then
		print("Player is in range")
	end
end

So this does work, however If i wanted a really vast amount of NPC objects, I feel like this could get messy and inefficient really quick. I've also heard about Region3, but I'm not sure if that would be a good choice either.

If someone knows a bit more about this than me and is willing to share, I'd appreciate it!

Roblox's Dialog has a property called ConversationDistance which disables the Dialog until the Player's Character is within range. That's the baked-in solution.

If you are using a custom implementation of NPC dialogue, just check the magnitude whenever a Player attempts to initiate the dialogue (i.e clicks on the npc or shoots at it or something)