What detail mode are you on? Specs? Can you post a log (My Games\Chivalry Medieval Warfare\UDKGame\Logs) just for fun?
A few things happen when you kill someone. Best probably incorrect guess off the top of my head would be an I/O issue, possibly your HDD parking (is it a laptop drive? A WD Green or other eco-friendly drive?), then taking time to spin up when textures for the decap mesh need loading. But then, they’re likely already loaded, making that a pretty poor guess.
Not listed on the dxdiag for some reason, but I use a Nvidia Geforce 540M (and I have forced the game to use it).
I was thinking about an issue with the hdd too, maybe when the game edit UDKStats.ini. However, I’ve met a few people in-game or on Reddit with the same problem recently.
I will try to crank the graphics down a bit and then send you my logs.
Thanks for listening to me :)
Edit: And here is my last log: http://pastebin.com/ytbzRUi1
Tried to reduce the graphics but it didn’t change anything.