Fix a Slow Windows PC After Connecting an External Monitor (2026)

How to Fix a Slow Windows Device After Connecting an External Monitor

Some people use their Windows laptop connected to an external monitor to get a larger screen area, but this may cause unexpected problems, such as lag or performance issues. If you have suffered from this kind of problem, here are some solutions that may be effective in fixing it.

Is Your Computer Compatible With the External Monitor?

One of the most important causes of lag on a Windows laptop is the lack of the simple hardware requirements needed to support the monitor. This usually happens when the laptop's graphics card is not powerful enough to handle the monitor's resolution. Try reducing the external monitor's resolution to see whether that fixes the problem.

How Do You Change the Monitor's Refresh Rate?

The refresh rate is the number of times the image is updated per second. If the laptop's graphics card or integrated graphics is not powerful enough to handle a higher refresh rate, it may struggle to keep up with the increasing frames, causing stuttering or tearing in the image. You can try changing your laptop's monitor refresh rate to see whether the problem is resolved. First, press Win + I to open the Settings app. Go to System > Display > Advanced display. Click Display adapter properties for Display 1. Go to the Monitor tab and click the Screen refresh rate drop-down to select 60 Hertz. Press Apply, then OK.

How Do You Run the Hardware Troubleshooter?

The hardware troubleshooter in Windows can help fix all kinds of problems with external devices. It can scan the system to detect any irregularities and try to resolve them. To run the Hardware and Devices troubleshooter in Windows, press Win + X to open the power user menu. Select Run from the menu. Type msdt.exe -id DeviceDiagnostic in the text field and press Enter. In the Hardware and Devices window, click Advanced and check the Apply repairs automatically box. Click Next to run the troubleshooter, and let it detect and fix any problems. Afterward, check whether the Windows laptop still lags when connected to an external monitor.

How Do You Close Unnecessary Apps and Programs?

The performance issues you are facing may be caused by the apps and programs running on your computer. You can try closing unwanted apps and programs to see whether that fixes the problem. Press Ctrl + Shift + Esc to open Task Manager. In the Processes tab, find the program you do not need and select it, then click the End task option at the top. Close all unwanted apps and programs and check whether you still experience lag.

What General Fixes Can You Try?

Still facing the problem? Do not worry, you can try the following general solutions to fix it. Update your graphics drivers, since an outdated or incompatible graphics driver may be the reason for the Windows laptop's lag, so it is good to update them if you have not already. Try a clean boot, which can help identify whether a third-party program or service is causing the lag; if you do not experience any lag during a clean boot, you will need to uninstall any suspicious apps or programs to fix the problem. Install Windows updates, since a buggy Windows version can cause such anomalies, so as a last resort, try installing any pending Windows updates to see whether they solve the problem. With these steps, there will be no more lag when using an external monitor with your Windows laptop.