Check flash storage consistency after a Windows update

Your storage test results changed after a Windows update, or file transfers now seem slower and less consistent. That does not automatically mean the drive has failed. Updates can leave background tasks running, and a browser test can vary with other work happening on the computer.

Use the Storage Test to compare large-file speed and small-write performance under repeatable conditions. The results can help you spot a change, but they cannot confirm whether a drive is healthy or identify every cause of slow storage.

Test storage after the update

1. Open the Storage Test in the browser you normally use. Run the test once and note the large-file result, small-write result, and score.
2. Keep the computer in the same condition for each run. Use the same browser, power source, and connected drives. Do not run a second benchmark at the same time.
3. If Windows just finished installing an update, restart the computer if it has not restarted yet. Wait a few minutes after signing in, then close downloads, file transfers, and apps that are doing heavy work.
4. Run the Storage Test again. Compare the two results rather than relying on one run. If you have older results, compare those only when the browser and test conditions were similar.

If you changed browsers or cleared browser data since the earlier test, treat that as a different test setup. Browser storage benchmarks measure work available through the browser, not every part of the drive in isolation.

What the result means

The second run is close to the first

Small differences are normal. Background activity, browser scheduling, and other system work can change a result from one run to the next. If the computer feels normal and the scores are broadly similar, there may be no persistent storage slowdown to fix.

Both large-file and small-write results stay lower

A repeatable drop suggests that the change is not just a single unusual run. It still does not prove the storage device is faulty. Check for background work, low free space, a changed power mode, or a different test environment before blaming the drive.

Large-file results look normal, but small writes are slower

Large transfers and many small writes are different workloads. Small writes can be affected by background app activity, file indexing, security scans, or the storage device's own cache. A slower small-write result alone is not evidence that Windows damaged the drive.

Results jump around between runs

Look for changing conditions. A cloud sync, update task, antivirus scan, or another open browser tab can interrupt a run. Repeat the test when the computer is idle and compare results under the same conditions.

The score is low, but everyday use seems fine

A score is a comparison within this browser test, not a pass or fail grade for the whole computer. It does not test every file operation or diagnose drive wear. For what a browser speed test can and cannot reveal about drive health, see Why a storage test is not a SMART diagnostic.

How to fix a slowdown

1. Restart after the update. A restart can finish setup tasks and release resources held by programs. If Windows Update says a restart is pending, restart before comparing results again.
2. Wait for background work to finish. Pause large downloads, cloud sync, file copies, and app updates, then let the computer sit idle for several minutes. In Task Manager, check whether a process is still using the disk heavily before you run another test.
3. Test while connected to power. On Windows 11, open Settings › System › Power & battery and check Power mode. On a Mac, open System Settings › Battery and check whether Low Power Mode is enabled. Use consistent power settings when comparing runs.
4. Check available space. On Windows 11, open Settings › System › Storage. On macOS, open System Settings › General › Storage. If the system drive is nearly full, remove or move files you no longer need, then test again. Do not delete unfamiliar system files to make room.
5. Repeat in a clean browser session. Close extra tabs and pause extensions that may be doing work in the background. Then rerun the test in the same browser. A different browser can use different storage and security rules, so its score is not a direct before-and-after comparison.
6. Check for a broader drive problem. If file copies, app launches, and the browser test are all consistently slow, back up important files first. Then use your computer or drive manufacturer's storage diagnostics, or ask a repair professional to check the drive. Avoid repeated stress tests if you are hearing unusual drive noises or seeing file errors.

When it may be the storage device

A benchmark result by itself cannot diagnose a failing SSD, hard drive, USB flash drive, or memory card. Be more concerned if the slowdown continues after restarts and idle testing, normal file copies also stall, files become unreadable, or the operating system reports storage errors. Back up important data before running further checks or attempting repairs.

If only an external flash drive is affected, reconnect it directly to the computer instead of through a hub, and try another port or cable if available. If the same drive fails on another computer too, stop relying on it for important files and replace it or contact the seller. A speed test is not a capacity or data-integrity check.

Why an update can change a result

After an update, Windows may still be indexing files, checking security, syncing data, or completing other maintenance. Those tasks compete for storage access, especially when many small reads and writes happen at once. Let them finish before testing. If results remain different, compare them with the same browser and conditions, and use an operating-system or manufacturer diagnostic for drive health rather than treating the browser score as a diagnosis.