多线程socket 端口扫描程序，实现了，但是速度不行，求指点。

#pragma comment(lib,"ws2_32.lib")
#include <stdio.h>
#include <winsock2.h>
#define MAXTHREAD 500
#define PORTSTART 1
#define PORTEND 60000
#define TIMEOUT 1
#define WAITTIME 10
#define IP "61.135.169.105"  //百度地址
FILE * logHandle;
DWORD PortScan(LPVOID lp);
typedef struct
{
    SOCKET s;
    sockaddr_in addr;
} mySocket;//传递参数
int threadCount = 0;
CRITICAL_SECTION c;
int main()
{
    
    WSADATA ws;
    InitializeCriticalSection(&c);
    fopen_s(&logHandle,"C:\\Documents and Settings\\Administrator\\桌面\\log.txt","w+");
    int nRet = WSAStartup(MAKEWORD(2,2),&ws);
    if(nRet !=0)
    {
        fprintf(logHandle,"Failed to initial the socketdll,%ld\n",WSAGetLastError());
        return 1;
    }
    for(int i=PORTSTART;i<=PORTEND;i++)
    {    
        mySocket *listenSocket = new mySocket;
        listenSocket->s = socket(AF_INET,SOCK_STREAM,0);
        if(listenSocket->s == INVALID_SOCKET)
        {
            fprintf(logHandle,"create socket error with %ld\n",WSAGetLastError());
            return 1;
        }

        listenSocket->addr.sin_addr.s_addr = inet_addr(IP);
        listenSocket->addr.sin_family = AF_INET;
        memset(listenSocket->addr.sin_zero,0,8);
        listenSocket->addr.sin_port = htons(i); //创建监听的socket
        

        while(threadCount >MAXTHREAD)
        {
            Sleep(5000);
        }
        if(CreateThread(NULL,0,(LPTHREAD_START_ROUTINE)PortScan,(LPVOID)listenSocket,NULL,NULL))
        {
            threadCount ++;
        }
    }
    while(threadCount >0)
    {
        Sleep(5000);
    }
    WSACleanup();

    return 0;
}
DWORD PortScan(LPVOID lp)
{
    int nRet;
    mySocket *s = (mySocket *)lp;
    //EnterCriticalSection(&c);
    int port = ntohs(s->addr.sin_port);

    connect(s->s,(sockaddr *)&s->addr,sizeof(sockaddr_in));
    unsigned long flag = 1;
    nRet = ioctlsocket(s->s,FIONBIO,&flag);
    if(nRet != 0)
    {
        fprintf(logHandle,"ioc error with %ld\n",WSAGetLastError());
    }
    fd_set mask;
    FD_ZERO(&mask);
    FD_SET(s->s,&mask);
    struct timeval tm = {1,0};
    switch(select(0,NULL,&mask,NULL,&tm))
    {
    case -1:
        fprintf(logHandle,"%d port connect error %ld\n",port,WSAGetLastError());
        break;
    case 0:
        fprintf(logHandle,"%d port time out\n",port);
        break;
    default:
        fprintf(logHandle,"%d port open\n",port);
    }
    closesocket(s->s);
    threadCount --;
    delete s;
    //LeaveCriticalSection(&c);
    return 0;
}