How to compare a cool start with a heavy load

Your computer feels quick when you first start working, then slows down after a demanding task. Comparing a cool-start result with a result after sustained load can help show whether performance drops as the computer heats up.

Use the Overheating Test to apply a full load for a few minutes, then compare processor scores from before and after. The test can show a slowdown under load, but a browser cannot read your processor's exact temperature.

Compare a cool start with a heavy load

1. Open the Processor Test and the Overheating Test. Keep both in the same browser for the comparison.
2. Let the computer sit idle for about 10 minutes. Keep it in the same room and on the same surface you will use for the second test. Do not put it in a refrigerator or use another artificial cooling method.
3. Run the Processor Test and note its score out of 100. Also note whether the computer is plugged in, which power mode is active, and any obvious background activity.
4. Run the Overheating Test and let its full-load test continue for a few minutes. Stop if the computer becomes unusually hot, makes concerning noises, or shuts down.
5. As soon as the heavy-load test ends, run the Processor Test again under the same conditions. Write down the second score and whether the computer still feels slow.
6. Let the computer return to idle for about 10 minutes, then repeat the comparison once. A repeated pattern is more useful than one pair of scores.

Keep other demanding apps closed, avoid changing browser tabs during the tests, and do not install updates or switch power modes between runs. If you are comparing a laptop, keep it plugged in for both processor tests, or run both on battery. Mixing power states can change the result.

What the result means

The second score is close to the first

A small difference can happen because the operating system schedules work differently from one run to the next. If repeated scores stay close and the computer remains responsive, this test did not find a clear load-related slowdown. It does not rule out every intermittent heat or power issue.

The second score is noticeably lower more than once

A repeated drop after the heavy-load test suggests the processor is doing less work under the later conditions. Heat can cause a processor to reduce its speed to protect itself. This is called thermal throttling. Power limits, background tasks, or a different power mode can also lower a score, so the result is evidence of a performance change, not proof of overheating.

To estimate the relative drop, use ((cool score - post-load score) / cool score) × 100. For example, a change from 80 to 72 is a 10 percent drop. Treat it as a comparison, not a pass or fail threshold.

The scores vary widely between repeats

Conditions may be changing too much for a clear comparison. A download, browser tab, system update, or other active program can compete for processor time. Close unnecessary work, wait for the computer to settle, and repeat with the same browser and power state.

The score is stable, but the computer still feels slow

The cause may not be processor heat. Storage activity, memory pressure, a slow network, or one busy app can make the whole computer feel sluggish. Check whether the slowdown occurs only in a particular program, and use the system's activity view to see what is busy.

How to make the comparison more reliable

1. Keep the surface and vents clear. Place a laptop on a hard, flat desk, not a blanket or cushion. Do not cover the vents or block a desktop's airflow.
2. Check for background work. On Windows 11, open Task Manager with Ctrl + Shift + Esc and check the CPU column. On macOS, open Activity Monitor and select the CPU tab. Wait for heavy background activity to finish before comparing.
3. Use one power mode for both runs. In Windows 11, open Settings › System › Power & battery and check Power mode. On macOS, open System Settings › Battery and keep Low Power Mode in the same state for both runs. Available options can vary by device.
4. Check the cooling path. Move the computer away from soft surfaces and make sure air can reach its vents. If a fan is obstructed by dust, follow the manufacturer's cleaning guidance rather than pushing objects into the vents.
5. Repeat after a proper cool-down. Leave the computer idle until it feels and sounds settled, then compare again. Do not run full-load tests over and over without a break.

When to arrange service

A single lower score is not enough to diagnose a fault. Consider service if the computer repeatedly slows or shuts down under ordinary workloads, its fans make new grinding or rattling sounds, or it becomes extremely hot even when its vents are clear. If it is under warranty, contact the manufacturer before opening it. For an older device, a repair shop can inspect the fan, heatsink, and internal cooling system.

What a browser test can and cannot show

The Processor Test measures work performed in the browser and reports a score. It does not measure the processor's exact temperature, inspect the cooling hardware, or identify a defective component. The Overheating Test gives the computer a sustained workload so you can observe whether performance changes, but it cannot tell you the precise cause. Use the scores as a controlled comparison, then check cooling and power conditions before deciding whether the computer needs repair.