First of all, check whether the keyboard lag is happening in just games or all your apps on Windows. If you are experiencing Typing delay generally, you can try running the Keyboard troubleshooter ...

The keyboard is a popular peripheral, but few games move beyond the common WASD controls and pursue typing and transcription ...

But if you're used to playing PC games, you might miss the precision of a keyboard and mouse. Luckily, you don't have to leave that feeling behind. Can you use a keyboard and mouse with your PS4?