Fix LocalServiceNoNetworkFirewall High CPU Usage in Windows
Fix LocalServiceNoNetworkFirewall High CPU Usage in Windows
You open Task Manager because your computer suddenly feels slow.
The cooling fan is running constantly. Applications take longer to open. The system becomes sluggish even when you are not doing anything demanding.
After sorting processes by CPU usage, you discover a process called:
LocalServiceNoNetworkFirewall
consuming a significant amount of processor resources.
Many users immediately assume the process is malware because the name looks unusual. In reality, it is a legitimate Windows service group that includes components related to Windows Defender Firewall and other network-related services.
Under normal conditions, this process should use very little CPU. If it consistently consumes large amounts of processor time, something else is usually triggering the behavior.
This guide explains what the process does, why it causes high CPU usage, and how to fix it.
What Is LocalServiceNoNetworkFirewall?
LocalServiceNoNetworkFirewall is a Service Host group used by Windows.
It typically hosts services running under the Local Service account while restricting network access.
Common services associated with this group may include:
- Windows Defender Firewall
- Base Filtering Engine (BFE)
- Network-related system services
- Security filtering components
Because multiple services share the same host process, Task Manager may only display the group name instead of the individual service responsible for the problem.
Why High CPU Usage Happens
Several issues can trigger excessive CPU usage.
| Cause | Impact |
|---|---|
| Corrupted firewall rules | Continuous processing |
| Windows Update issues | Increased service activity |
| Malware interference | Excessive resource usage |
| Third-party security software | Service conflicts |
| Corrupted system files | Service instability |
| Damaged Windows Firewall configuration | High CPU utilization |
| Network driver issues | Constant service retries |
In many support cases, the root cause is not the firewall itself but another component interacting with it.
Common Symptoms
Users often notice:
- CPU usage above 20% to 80%
- Constant fan noise
- Slow application launches
- Reduced battery life
- High temperature readings
- System lag while browsing
- Task Manager showing Service Host activity
The issue may appear after:
- Windows updates
- Antivirus installations
- Driver updates
- Malware removal
- Network configuration changes
Step-by-Step Solution
Step 1: Restart the Computer
It sounds simple, but temporary service issues can sometimes be cleared by a reboot.
After restarting:
- Open Task Manager.
- Monitor CPU usage for several minutes.
- Check whether the process returns to normal.
If usage remains high, continue troubleshooting.
Step 2: Identify the Actual Service
Task Manager can reveal which service is causing the load.
- Open Task Manager.
- Expand the Service Host entry.
- Review individual services.
Look for:
- Windows Defender Firewall
- Base Filtering Engine
- Security-related services
Identifying the specific service makes troubleshooting much easier.
Step 3: Run Windows Troubleshooter
Open:
Settings → System → Troubleshoot → Other Troubleshooters
Run available network and system maintenance troubleshooters.
While not always successful, they can resolve common service configuration problems.
Step 4: Repair System Files
Open Command Prompt as Administrator.
Run:
sfc /scannow
Allow the scan to complete.
If corruption is found, restart the computer.
Corrupted system files are a surprisingly common cause of unusual service behavior.
Step 5: Run DISM
If SFC reports issues or the problem continues:
DISM /Online /Cleanup-Image /RestoreHealth
After completion:
sfc /scannow
Again, restart the computer.
This combination resolves many Windows service-related problems.
Advanced Troubleshooting
Reset Windows Firewall
Corrupted firewall policies can trigger excessive processing.
Open Command Prompt as Administrator:
netsh advfirewall reset
Restart Windows.
Important:
Custom firewall rules will be removed.
If the computer belongs to a business environment, verify policies before performing this step.
Check for Security Software Conflicts
Running multiple security products simultaneously can create service conflicts.
Review installed applications for:
- Third-party firewalls
- Internet security suites
- Endpoint protection tools
Temporarily disable or remove conflicting software for testing.
Check Event Viewer
Event Viewer often contains clues.
- Press Windows + X.
- Select Event Viewer.
- Review:
- System Logs
- Application Logs
- Security Logs
Look for repeated firewall, service, or network-related errors.
Perform a Malware Scan
Although the process itself is legitimate, malware can interact with Windows services.
Run:
- Windows Defender Offline Scan
- Full system scan
- Additional malware scanner if necessary
Unexpected service activity should always be investigated.
Compare Normal vs Problematic CPU Usage
| Condition | Expected CPU Usage |
| Idle system | 0% to 2% |
| Normal activity | 1% to 5% |
| Brief update activity | 5% to 20% |
| Persistent problem | 20% to 100% |
Short spikes are normal.
Constant high usage is not.
Prevention Tips
Keep Windows Updated
Many service-related bugs are corrected through cumulative updates.
Avoid Multiple Firewalls
Using more than one firewall solution often causes conflicts.
Monitor Startup Applications
Unnecessary startup programs can increase service load.
Perform Regular System Health Checks
Monthly maintenance helps detect corruption early.
Commands worth running periodically:
sfc /scannow
and
DISM /Online /Cleanup-Image /RestoreHealth
Maintain Updated Network Drivers
Driver issues can indirectly affect service host processes.
LocalServiceNoNetworkFirewall is a legitimate Windows component, but it should not continuously consume large amounts of CPU resources.
Most cases can be resolved by identifying the underlying service, repairing system files, resetting Windows Firewall, updating drivers, and checking for software conflicts.
If the process continues using excessive CPU after these steps, investigate Event Viewer logs and perform a thorough malware scan before considering more advanced recovery options.
At GetQuickTechSupport.com, this type of issue is commonly traced back to firewall corruption, security software conflicts, or damaged Windows components rather than the process itself.
Frequently Asked Questions (FAQ)
Is LocalServiceNoNetworkFirewall a virus?
No. It is a legitimate Windows service host group. However, malware can sometimes interact with services running under it.
Why is it using so much CPU?
Common causes include corrupted firewall settings, damaged system files, security software conflicts, or Windows service issues.
Can I disable LocalServiceNoNetworkFirewall?
Directly disabling it is not recommended because it contains important Windows services.
Will resetting Windows Firewall help?
In many cases, yes. Corrupted firewall configurations are a common cause of excessive activity.
Should I reinstall Windows?
Reinstallation should be considered only after standard troubleshooting methods fail.