Hi Brandon, my name is Neil, and I'm a Windows 10 user like you.
I'll be happy to help you with your question.
Sorry you're experiencing lag with your external monitor.
Normally, updating your monitor and GPU drivers will fix this issue.
To update your GPU driver, please make sure you get this driver from your laptop manufacturer (Asus). The reason for this is that laptop GPU's have slight modifications made to the driver architecture to get the best performance out of the GPU and the custom system.
These drivers can only be found on Asus. If you download the driver direct from the GPU manufacturer (NVIDIA or AMD), these drivers are missing these small modifications and can cause issues with your system.
Also, don't worry if a GPU driver appears to be old. This is normal, as laptop manufacturers don't release a lot of GPU drivers. They only release ones that work and are fully supported, so these tend to be older in contrast to a GPU manufacturer's drivers release schedule.
To check for any updates for your monitor, please do the following:
Right click your Windows Start button.
Click on "Device Manager"
In Device Manager, expand the section ">Monitors" and locate your monitor.
Right click your monitor and then click on "Update driver".
Click on "Search automatically for drivers".
See if it finds any updated drivers for your monitor.
If none are found, click on "Search for updated drivers on Windows Update" and see if you can find any drivers there.
Please do let me know how you get on.
Kindest regards,
Neil