Game is downloading something during play

I've serious issue since update to 0.8.6 , the game is downloading some cryptic files during play ruining my ping. The names of the files are always long and random like: a9fhi8dfyhuiwueh88347yoihfg8673948ygh.pk3 It's just random letters and numbers with pk3 extension. Can you help? How to turn that crap off?

I've never had that problem as far as I could tell. Maybe make it to where everything is downloaded before entering a server. Better yet, I try to join an encrypted one, just to ensure I can do fine. As for that type of nonsense, a good way to do that is making your own server, setting it for yourself, and playing there.

thats a pk3 served by the radio mod used by some servers. nothing harmful. also you can just type "radio off" in console to stop those

It was written I could type "radio off" in the console, so I did and it said unknown command or something like that.