CPU usage increasing over time TCP/IP

#include <windows.h>
#include  <stdlib.h>
#include <stdio.h>
#include <winsock.h>
#include "mingw.thread.h"

// our thread for recving commands
DWORD WINAPI receive_cmds(LPVOID lpParam) 
{
// Here I changed for our needs ! its a warehouse management system.  
  printf("thread created\r\n");
  
  // set our socket to the socket passed in as a parameter   
  SOCKET current_client = (SOCKET)lpParam; 
  
  // buffer to hold our recived data
  char buf[100];
  // buffer to hold our sent data
  char sendData[100];
  // for error checking 
  int res;
  
  // our recv loop
  while(true) 
  {
	 res = recv(current_client,buf,sizeof(buf),0); // recv cmds
	 
	 Sleep(10);
	 
	 if(res == 0)
	 {
	  MessageBox(0,"error","error",MB_OK);
	  closesocket(current_client);
	  ExitThread(0);
	 }
	 
	 if(strstr(buf,"hello"))
	 { // greet this user
	   printf("\nrecived hello cmd");
	   
	   strcpy(sendData,"hello, greetz from KOrUPt\n");
	   Sleep(10);
	   send(current_client,sendData,sizeof(sendData),0); 
	 }								
	 else if(strstr(buf,"bye"))   
	 { // dissconnected this user
	   printf("\nrecived bye cmd\n");
	   
	   strcpy(sendData,"cya\n");
	   Sleep(10);
	   send(current_client,sendData,sizeof(sendData),0);
 
	  // close the socket associted with this client and end this thread
	   closesocket(current_client);
	   ExitThread(0);
	 }
	 else
	 {
	   strcpy(sendData,"Invalid cmd\n");
	   Sleep(10);
	   send(current_client,sendData,sizeof(sendData),0);
	 }
	 
	 // clear buffers
	   strcpy(sendData,"");
	   strcpy(buf,"");
   }
}   

int main()
{
 printf("Starting up multi-threaded TCP server by KOrUPt\r\n");
 
 // our masterSocket(socket that listens for connections)
 SOCKET sock;
 
 // for our thread
 DWORD thread; 
 
 WSADATA wsaData;
 sockaddr_in server;
 
 // start winsock
 int ret = WSAStartup(0x101,&wsaData); // use highest version of winsock avalible
 
 if(ret != 0)
 {
	return 0;
 }
  
 // fill in winsock struct ... 
 server.sin_family=AF_INET; 
 server.sin_addr.s_addr=INADDR_ANY; 
 server.sin_port=htons(123); // listen on telnet port 23
 
 // create our socket
 sock=socket(AF_INET,SOCK_STREAM,0); 
 
 if(sock == INVALID_SOCKET)
 {
	return 0;
 }
  
 // bind our socket to a port(port 123) 
 if( bind(sock,(sockaddr*)&server,sizeof(server)) !=0 )
 {
	return 0;
 }
  
 // listen for a connection  
 if(listen(sock,5) != 0)
 {
	return 0;
 }
 
 // socket that we snedzrecv data on
 SOCKET client;
 
 sockaddr_in from;
 int fromlen = sizeof(from); 
  
 // loop forever 

 while ((client = accept(sock, (struct sockaddr*)&from,&fromlen))!= INVALID_SOCKET) 
{
  // accept connections
  client = accept(sock,(struct sockaddr*)&from,&fromlen);
  printf("Client connected\r\n");
  
  // create our recv_cmds thread and parse client socket as a parameter
  // CreateThread(NULL, 0,receive_cmds,(LPVOID)client, 0, &thread);   
// Reaplaced CreateThread with
std::thread th_client(receive_cmds,(LPVOID)client);
 }
 
 // shutdown winsock
 closesocket(sock); 
 WSACleanup(); 
 
 // exit
 return 0;
}