Fix Slow Network Copy Speeds in Windows 10/11 by Tuning SMB and Disabling Throttling

Fix Slow Network Copy Speeds in Windows 10/11 by Tuning SMB and Disabling Throttling​

Difficulty: Intermediate | Time Required: 20 minutes
Slow file transfers to a NAS, another PC, or a Windows file server can be frustrating—especially on gigabit (or faster) networks where you expect 100–110 MB/s but see 20–60 MB/s, inconsistent bursts, or a transfer that “ramps down” over time. In Windows 10/11, many of these symptoms come from a mix of SMB (Windows file sharing) features, client-side throttling behaviors, and network adapter offload settings.
This tutorial walks you through safe, measurable tweaks to improve SMB copy performance, reduce transfer slowdowns, and keep speeds stable—without disabling security features you still need.

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Prerequisites​

Before changing anything, make sure you have:

• Windows 10 or Windows 11 (any modern build; steps note where versions differ)
• Admin rights on the PC you’re tuning
• A wired Ethernet connection for testing (Wi‑Fi adds variables and is often the real bottleneck)
• A known-good target (NAS/Server/PC share) and a test file (5–20 GB recommended)
• Optional but helpful: access to the remote device’s admin UI (NAS/server) to confirm its SMB settings

Note: These changes primarily affect SMB file transfers (\server\share), not web downloads. Always benchmark before and after.

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Step-by-step: Measure first (baseline)​

1. Confirm link speed
   1. Go to Settings → Network & Internet → Ethernet.
   2. Click your adapter and check Link speed (should be 1.0 Gbps / 2.5 Gbps / 10 Gbps as expected).
2. Run a simple real-world copy test
   1. Copy a single large file (e.g., 10 GB) from PC → share and then share → PC.
   2. Note the MB/s Windows reports and whether it drops after a few seconds.
3. Optional: use a more accurate copy tool
   • Open Windows Terminal (Admin) and run:
     robocopy "C:\Test" "\\SERVER\Share\Test" bigfile.bin /J /R:0 /W:0 /NP
/J (unbuffered I/O) often shows steadier throughput on fast disks.

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Step-by-step: Verify SMB version and basic Windows SMB configuration​

1. Check your SMB client configuration
   1. Open Windows Terminal (Admin).
   2. Run:
      Get-SmbClientConfiguration
   3. Look for items such as:
      • EnableSecuritySignature
      • RequireSecuritySignature
      • DirectoryCacheLifetime, FileInfoCacheLifetime, etc.

Tip: On most home and SMB environments, performance issues are rarely due to SMB1/SMB2 choice (SMB1 should be off). They’re more often caused by signing requirements, offloads, or throttling behaviors.

1. Ensure SMB1 is disabled (recommended)
   • SMB1 is obsolete and insecure.
     1. Open Control Panel → Programs → Turn Windows features on or off.
     2. Make sure SMB 1.0/CIFS File Sharing Support is unchecked.
     3. Reboot if Windows requests it.

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Step-by-step: Reduce SMB slowdowns caused by unnecessary signing (where appropriate)​

SMB signing improves integrity (protects against tampering), but on some systems—especially older NAS devices, low-power servers, or certain NIC/CPU combos—it can reduce throughput.

1. Check whether signing is required
   1. Run (Admin PowerShell):
      Get-SmbClientConfiguration | Select EnableSecuritySignature,RequireSecuritySignature
      • If RequireSecuritySignature is True, Windows will enforce signing for SMB connections, which can slow transfers.
2. If you’re on a trusted LAN, consider not requiring signing
   • Only do this on a trusted, private network (home lab) where you control devices.
   • Run (Admin PowerShell):
     Set-SmbClientConfiguration -RequireSecuritySignature $false
   • You can keep signing enabled but not required (often a good balance):
     Set-SmbClientConfiguration -EnableSecuritySignature $true

Warning: Disabling/relaxing signing may reduce protection against certain man-in-the-middle scenarios. If this is a corporate network or you use untrusted segments, do not change this.

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Step-by-step: Disable Windows network throttling (Multimedia scheduler throttling)​

Windows includes a “network throttling” mechanism tied historically to multimedia scheduling. On some systems it can contribute to inconsistent throughput or lower sustained SMB copy speeds—especially when the system thinks it’s prioritizing audio/video responsiveness.

1. Back up the registry key
   1. Press Win + R, type regedit, press Enter.
   2. Navigate to:
      HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfile
   3. Right-click SystemProfile → Export (save a .reg file).
2. Set NetworkThrottlingIndex to “disabled”
   1. In the same key, find NetworkThrottlingIndex.
      • If it doesn’t exist: Right-click → New → DWORD (32-bit) Value
   2. Set its value to:
      • Hex: ffffffff
      • Decimal: 4294967295
   3. Click OK.
3. (Optional) Increase system responsiveness
   • In the same location, you may see SystemResponsiveness.
   • Some users set it to 0 (decimal) for maximum responsiveness to network tasks.
   • If present, set to 10 or 0 based on your use (gaming/streaming vs file server).
   • When in doubt, leave it alone.
4. Reboot
   • This change typically requires a reboot to fully apply.

Note: This tweak is widely used in performance tuning guides, but it’s not “officially recommended” for every scenario. Test and revert if you notice audio/video stutter or no improvement.

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Step-by-step: Tune NIC settings that commonly impact SMB throughput​

Driver offloads and power-saving features can cause odd SMB behavior: bursty transfers, high CPU, pauses, or low throughput.

1. Update your network adapter driver
   1. Open Device Manager → Network adapters.
   2. Right-click your Ethernet adapter → Properties → Driver.
   3. Prefer the latest driver from Intel/Realtek/Broadcom or your PC/motherboard vendor.
2. Disable Energy Efficient Ethernet (EEE) (common fix)
   1. Adapter Properties → Advanced tab.
   2. Look for:
      • Energy Efficient Ethernet
      • Green Ethernet
      • Power Saving Mode
   3. Set to Disabled.
   4. Click OK.
3. Check RSS (Receive Side Scaling) and offloads
   • In Advanced settings, consider:
     • Receive Side Scaling (RSS): Enabled (usually best)
     • Large Send Offload v2 (IPv4/IPv6): Try Enabled first; if you get pauses or weird drops, test Disabled
     • Checksum Offload: Usually Enabled
   • There’s no single “best” for all NICs. Change one setting at a time and retest.
4. Set adapter power management to prevent sleep
   1. Adapter Properties → Power Management tab.
   2. Uncheck Allow the computer to turn off this device to save power.

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Step-by-step: Retest and validate improvements​

1. Re-run the same copy test
   • Use the same file, same direction (PC→share and share→PC), and note sustained MB/s.
2. If you want clearer performance numbers, use Performance Monitor
   • Open perfmon and monitor:
     • Network Interface → Bytes Total/sec
     • SMB Client Shares counters (Windows 10/11 availability varies)

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Tips & Troubleshooting Notes​

• Wi‑Fi vs Ethernet: If you’re testing over Wi‑Fi, expect variability. For meaningful SMB tuning, test on Ethernet first.
• Disk speed matters: If either side is on a slow HDD (or SMR drive), SMB tuning won’t overcome disk write limits. Watch disk usage in Task Manager → Performance.
• NAS/Server SMB settings: Many NAS devices have SMB tuning toggles (SMB3, signing, encryption, opportunistic locking). If your NAS CPU is weak, disabling encryption/signing on the NAS (where safe) can help.
• SMB encryption: If SMB encryption is enabled on the share, it can heavily tax CPUs. Use it only where needed.
• Jumbo frames: Only enable jumbo frames if every device on the path supports it correctly (PC NIC + switch + NAS). Misconfigured jumbo frames often reduce performance.
• How to revert the throttling tweak: Re-import the exported .reg file or set NetworkThrottlingIndex back to its default (commonly 10 decimal on many systems).

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Conclusion​

By verifying SMB settings, relaxing unnecessary signing requirements (only on trusted networks), disabling Windows network throttling, and tuning common NIC power/offload options, you can often turn unstable or slow SMB transfers into consistent, high-throughput copies—especially on gigabit+ wired networks. The key is to benchmark before/after and change one variable at a time so you can keep only what helps.
Key Takeaways:

• Improve sustained SMB copy speeds by reducing throttling and avoiding unnecessary overhead.
• NetworkThrottlingIndex can help stabilize throughput on some Windows 10/11 systems.
• SMB signing requirements and NIC power-saving/offload settings are common performance bottlenecks.
• Measure results with consistent file copy tests and revert changes that don’t help.

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This tutorial was generated to help WindowsForum.com users get the most out of their Windows experience.