How VPNs Affect Speed Tests

Turn on a VPN, run a speed test, and the numbers almost always drop compared to your baseline connection. It's easy to assume the VPN itself is simply "slow," but what's actually happening is a combination of a few specific, explainable effects — and understanding them helps you test (and choose a VPN) more fairly.

What a VPN Actually Does

A VPN encrypts your traffic and routes it through an intermediary server before it continues to its real destination. Instead of your device talking directly to a website or test server, it talks to the VPN server, which then talks to the destination on your behalf. That's an extra hop and an extra layer of processing added to every single packet — the price paid for the privacy and security a VPN provides.

Encryption and Processing Overhead

Every packet has to be encrypted on your device and decrypted on the VPN server (and the reverse on the way back), which costs CPU time on both ends. Modern protocols keep this fairly small — WireGuard, for example, is considerably lighter than older OpenVPN configurations — but it's never exactly zero.

Routing Distance — Usually the Bigger Factor

In practice, this tends to matter more than encryption overhead itself: if the VPN server is physically far from you, or far from wherever your traffic is ultimately headed, you've added real distance to every round trip. Since latency rises with distance, and TCP throughput is itself sensitive to round-trip time, a distant VPN server can noticeably cap your effective speed even on a connection that's fast with the VPN off.

Server Load and Shared Bandwidth

A VPN server's own internet connection is finite and shared across everyone connected to it at that moment. A popular server during peak hours — especially on free or budget VPN services — can bottleneck every user on it regardless of how fast any individual user's own connection is.

Testing Speed Fairly With a VPN

• Run a baseline test with the VPN off first, so you have a genuine number to compare against.
• Test again immediately after connecting, before other conditions (time of day, network load) change.
• Remember you're not just testing "VPN vs. no VPN" — different VPN server locations will produce different results even on the same VPN service.

Tips for Faster VPN Speeds

• Pick the nearest server with a low ping to you, not just the one labeled "fastest."
• Prefer modern protocols like WireGuard or IKEv2 over older OpenVPN-over-TCP configurations where your VPN app supports it.
• Avoid obviously overloaded or heavily advertised "free" server locations during peak hours.
• Use a wired connection so Wi-Fi variability doesn't compound with the VPN's own overhead — see our Wi-Fi vs. Ethernet guide.

Key Takeaways

• A VPN adds encryption overhead and an extra routing hop to every packet — both cost some speed.
• Server distance usually matters more than encryption overhead itself.
• Test with the VPN off first to get a genuine baseline, then compare fairly.
• Server choice and protocol matter — not all VPN connections lose the same amount of speed.