A VPN routes your traffic through an intermediate server and encrypts it on the way. Both of those things are useful, and both of them cost performance. The question is not whether a VPN slows you down, but by how much and whether that matters for what you are doing.
Where the loss comes from
The detour
Instead of travelling directly to a website, your data goes to the VPN server first. If that server is in another country, you have added thousands of kilometres to every round trip. This is the dominant effect on latency, and no amount of software tuning removes it. It is physics.
Encryption
Your device encrypts every packet and the server decrypts it. Modern hardware handles this easily, so on a recent phone or laptop the cost is small. On older devices, or on a router doing the encryption for the whole household, it can become the limiting factor.
Server load and protocol
You share the VPN server with other subscribers, and a busy one is slower. The protocol matters too: WireGuard is generally faster and lighter than older OpenVPN configurations.
What to expect in practice
With a nearby server and a modern protocol, losing 5 to 15 percent of your download speed is typical, with latency rising by a handful of milliseconds. Connect to a server on another continent and both figures deteriorate sharply. Halved speed and a hundred extra milliseconds of ping is entirely ordinary.
Measure your own cost rather than guessing: run our speed test with the VPN off, then again with it on, and compare all four numbers. The latency change is usually more revealing than the speed change.
Keeping the cost down
- Choose the closest server that satisfies your reason for using the VPN.
- Prefer WireGuard where your provider offers it.
- Use split tunnelling so only the traffic that needs protection goes through the tunnel.
- Run it on the device, not the router, unless you specifically need whole-network coverage. Router hardware is often the weakest link.
- Test a few servers. Load varies enormously between locations on the same service.
When to switch it off
Turn the VPN off when you are running a speed test to establish a baseline, and consider disabling it for latency-critical activity such as competitive gaming or an important video call. The added delay and jitter are felt directly. Our guide to ping and jitter explains why those activities are so sensitive.
Frequently asked questions
Can a VPN ever make my connection faster?
Occasionally, in one narrow case: if your provider throttles particular traffic, encryption can prevent that from being identified. Otherwise a VPN adds work, not capacity.
Does a free VPN cost more speed?
Usually a great deal more. Free services are typically oversubscribed, and many fund themselves in ways that raise their own privacy questions.
Should I leave it on all the time?
That is a privacy decision rather than a performance one. If you do, use a near server and check occasionally that the cost has not crept up as loads shift.
