This is how you fix keyboard lag issue on the Acer Aspire 4520 Gemstone.
There are two separate ways that you can fix this issue:
The first fix is quite simple – disable the touchpad. Sorry touchpad users 🙁 Press Fn-F7 to turn it off. Remember you can easily plug in a usb mouse instead, or if you’re the geeky type learn to navigate through windows using hotkeys.
The second fix is to upgrade the BIOS to the latest version. This isn’t anywhere as scary as it sounds.
You want the file FBIOS3630.zip, which you can find here
Unzip the contents and run the file SWinFlash.exe – and point it to the file Z03_3630.WPH
If you’re the highly paranoid type, then before you do this create a factory restore disc via the Acer empowering framework. However this is an official patch, so unless you’ve done something truly strange to your laptop, then there’s no reason why updating the BIOS shouldn’t work.
Don’t ask me how this one made it past Acer QA :/