Speed · Plain-English answer
Yes, a little, because your traffic takes an extra hop through the VPN server and is encrypted along the way. On a well run network the loss is small, and modern protocols such as WireGuard keep overhead low. Distance to the server and server load matter far more than encryption itself.
Three things cost you speed with a VPN. The extra distance your packets travel to reach the server adds latency. Encryption adds a small processing cost on your device and the server. And the server itself shares its capacity among everyone connected to it at that moment.
Of these, geography and congestion dominate. Connecting from London to a busy server in Los Angeles will feel slow for reasons that have nothing to do with cryptography, while a quiet server in Amsterdam may be indistinguishable from your bare connection.
Test methodically rather than guessing. Run a speed test with the VPN off to establish your baseline, then run the same test connected to your usual server, and compare both throughput and ping. You can do this in a browser at /tools/speed-test/.
A modest drop is normal and rarely noticeable in daily browsing or HD streaming. If you are losing a large share of your baseline, the fix is usually a nearer or quieter server rather than abandoning the VPN. ROOT uses WireGuard throughout, which keeps protocol overhead about as low as it currently gets.
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