Speed · Plain-English answer
Only when the throttling targets specific traffic. If your provider slows video streams or peer to peer transfers, a VPN hides what the traffic is, so those rules cannot match it. If the provider slows your whole line, for example after a data cap, a VPN changes nothing.
Providers shape traffic by recognising it. Video streams, torrents and game downloads each have signatures, and a congested or policy driven network can slow those categories while leaving the rest alone. A VPN encrypts everything into a single uniform stream, so category based rules no longer find anything to match.
What encryption cannot hide is volume. If your plan throttles you after a monthly allowance, or your provider slows all traffic at peak times, the VPN's traffic is throttled along with everything else.
Compare the same activity with and without the VPN at the same time of day. If a video service crawls unprotected but runs cleanly through the tunnel, category throttling is the likely explanation. A general speed check at /tools/speed-test/ alongside a streaming test helps separate line problems from selective ones.
Bear in mind that speed test traffic itself is sometimes prioritised by ISPs, so a glowing test result with a stuttering stream is itself evidence of shaping.
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