How does UE4 manage input received from the computer?

I have developed an application which runs on my laptop (the client). This client-application captures key presses and sends them via UDP to another application, which is running on a remote machine. This application on the remote server then sends the incoming input events to a UE4 application, which is also running on the server.

I have it working, however, when I press and hold (for example) ‘w’ to move forward (remember, I press and hold client-side), the character in UE4 on the server moves only a tiny bit, despite holding the key down (yes, I am using the key down event and it is firing rapidly).

I was wondering, how does UE4 manage the input it receives from the OS? Does it pool the input commands? Does it only feed them to the movement controller at a certain rate (ie, does it synchronize with frame rate)?