Windows 11 High RAM Usage at Idle After Update Fix

What is Windows 11 high RAM usage at idle?

After recent 2026 cumulative updates, many Windows 11 users report memory usage sitting at 60-80% in Task Manager with nothing open — sometimes 5-10 GB higher than before the update. The PC feels sluggish, apps are slow to switch, and the In use figure on the Task Manager > Performance > Memory tab stays high even minutes after a clean reboot.

Some of this is by design (Windows caches data to speed things up), but a genuine post-update spike usually comes from a driver that fails to release memory, an over-eager preloading service, or a background update component leaking the non-paged pool.

When does it occur?

• Within hours of installing a monthly cumulative update
• At idle, with no user applications open
• Worse on machines with 8 GB or 16 GB of RAM
• After waking from sleep, with memory never dropping back down
• When the System process or Service Host entries climb in Task Manager
• Alongside high disk activity from indexing or update delivery

What is normal at idle?

| Installed RAM | Typical idle "In use" | Investigate above |

|---------------|-----------------------|-------------------|

| 8 GB | 2.5-4 GB | ~6 GB |

| 16 GB | 3.5-6 GB | ~9 GB |

| 32 GB | 4-7 GB | ~12 GB |

Common causes

• SysMain (formerly Superfetch) preloading apps into RAM — unnecessary on NVMe SSDs and often 2-5 GB
• NDU.sys (Network Data Usage driver) leaking the non-paged pool, never releasing packet buffers
• Delivery Optimization peer-to-peer update cache leaking memory (addressed in the April 2026 update)
• Too many startup apps relaunching after the update
• Windows Search Indexer rebuilding its database after the update
• Transparency and animation effects holding extra GPU/RAM
• A leaking third-party driver or antivirus filter

Step-by-step fixes

1. Find the culprit first — Open Task Manager > Details, click the Memory column to sort, and note the top consumer. Then open Resource Monitor (resmon) > Memory and watch Nonpaged pool; if it climbs steadily at idle, you have a driver leak (continue to step 3).

1. Disable SysMain — Press Win+R, type services.msc, find SysMain, set Startup type to Disabled, and Stop the service. On SSD systems this frees several GB with no real downside.

1. Stop the NDU.sys leak — Open regedit, go to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Ndu, double-click Start, change the value from 2 to 4, and reboot. This disables the Network Data Usage monitor, a confirmed non-paged pool leak source. Create a System Restore point first.

1. Disable Delivery Optimization — Go to Settings > Windows Update > Advanced options > Delivery Optimization and turn off Allow downloads from other PCs. If memory still leaks here, set its service (DoSvc) to Manual in services.msc.

1. Trim startup apps — Open Task Manager > Startup apps and disable anything you don't need at boot (chat clients, updaters, RGB software). These quietly reload after every update.

1. Throttle Windows Search Indexer — Settings > Privacy & security > Searching Windows, switch from Enhanced to Classic indexing, or pause it while the database finishes rebuilding after the update.

1. Turn off visual effects — Settings > Accessibility > Visual effects, turn off Transparency effects and Animation effects. Then run sysdm.cpl > Advanced > Performance Settings and choose Adjust for best performance.

1. Use PC Manager Boost — Install Microsoft PC Manager from the Store and click Boost to flush standby memory instantly, or run EmptyStandbyList.exe to clear the cached "standby" pool without a reboot.

If it still doesn't work

If the non-paged pool keeps growing, the leak is almost certainly a driver. Open an elevated PowerShell and run poolmon (from the Windows Driver Kit) to identify the leaking pool tag, then match it to a driver — outdated network, storage, or antivirus drivers are the usual offenders, so update or temporarily uninstall them. As a last resort, open Command Prompt as admin and run DISM /Online /Cleanup-Image /RestoreHealth followed by sfc /scannow to repair update damage. Microsoft has acknowledged elevated idle memory in some 2026 builds and is reducing the WinUI 3 footprint of system components in updates planned for mid-to-late 2026, so keep Windows Update current.