sdr_spew_level 0;net_droponsendoverflow 1;net_client_steamdatagram_enable_override 1

CSGO: Waited 'X'ms for SteamNetworkingSockets lock [ReceiveMessagesOnConnection] ~* spam FPS drop temp fix

sdr_spew_level 0 (can already help) - you can add configuration or initialization parameters

net_droponsendoverflow 1 - if the first is not enough

net_client_steamdatagram_enable_override 1 - if the second is not enough