NetworkThrottlingIndex: what it actually throttles, and why the advice is usually wrong
SHORT ANSWER
NetworkThrottlingIndex lives under SOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfile and limits non-multimedia network packet processing to roughly 10 packets per millisecond by default. Setting it to 0xFFFFFFFF disables that limit. The honest assessment: it can help on very high-throughput connections and does close to nothing for a typical game's traffic, which is nowhere near the throttle ceiling.
Exactly what it changes
Read straight from the application source. If a tool will not show you this, it is asking for trust it has not earned.
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfile
NetworkThrottlingIndex = 0xFFFFFFFF (disabled)
Removes the cap on non-multimedia network packet processing rate.
What it does
The throttle exists so that heavy network traffic cannot starve audio and video playback of CPU time. It caps packet processing for non-multimedia traffic.
A competitive game sends small packets at a modest rate — typically well under the throttle threshold — which is why the theoretical benefit rarely materialises.
When it helps
- Measurable on connections doing sustained high-throughput transfer alongside gaming.
- Can help when streaming and gaming simultaneously on the same machine.
When it hurts
- Removes a protection designed to keep audio playback smooth under network load. On a machine that streams, that protection may have been doing its job.
- For most players the change is unmeasurable, and it is frequently sold as a large FPS win. It is not one.
How to undo it
Delete the value to return to the Windows default, or set it back to 10 (0xA).
Verdict
Low risk, low reward. We include it because it is genuinely part of the latency picture on some systems, but anyone claiming it is a major FPS tweak is repeating folklore.
Related guides
Everything else we change is listed too
All 127 optimizations are published in full, with what each one does and which are free. You can apply any of them by hand using pages like this one — the tool exists to do it in one click and put it back after every Windows update.