I happens after some time working with profiler, connecting/disconnecting. Mantas said that this stack trace should be enough to understand the reason behind it (full stack attached in untitled.rtf)
2211 ProfilerDriver_Set_Custom_PropConnectedProfiler(int) (in Unity) + 60 [0xfee3fc]
+ 2211 ProfilerConnection::SetConnectedProfiler(unsigned long, bool) (in Unity) + 143 [0xc8b0cf]
+ 2211 GeneralConnection::SendMessage(unsigned long, GeneralConnection::MessageID, void const*, unsigned long) (in Unity) + 213 [0xc5c005]
+ 2211 GeneralConnection::Connection::SendMessage(GeneralConnection::NetworkMessage&, void const*) (in Unity) + 87 [0xc5b777]
+ 642 SocketStream::SendAll(void const*, unsigned long) (in Unity) + 76 [0xc6477c]
+ ! 342 BufferedSocketStream::WouldBlockError() const (in Unity) + 17 [0xc67f91]
+ ! : 342 BufferedSocketStream::IsConnected() const (in Unity) + 0,39,... [0xc67f50,0xc67f77,...]
+ ! 300 BufferedSocketStream::WouldBlockError() const (in Unity) + 0,21,... [0xc67f80,0xc67f95,...]
+ 625 SocketStream::SendAll(void const*, unsigned long) (in Unity) + 70,112,... [0xc64776,0xc647a0,...]
+ 563 SocketStream::SendAll(void const*, unsigned long) (in Unity) + 134 [0xc647b6]
+ ! 291 ThreadedSocketStream::Poll(unsigned long long) (in Unity) + 17 [0xc67fb1]
+ ! : 291 BufferedSocketStream::IsConnected() const (in Unity) + 0,36,... [0xc67f50,0xc67f74,...]
+ ! 272 ThreadedSocketStream::Poll(unsigned long long) (in Unity) + 0,17,... [0xc67fa0,0xc67fb1,...]
+ 381 SocketStream::SendAll(void const*, unsigned long) (in Unity) + 59 [0xc6476b]
+ 381 BufferedSocketStream::Send(void const*, unsigned long) (in Unity) + 0,16,... [0xc64a30,0xc64a40,...]