我正准备编写我的第一个SDL2程序，我想使移动成为可能，但它非常滞后

#include <iostream>
#include <SDL2/SDL.h>
#include <conio.h>

SDL_Window* window = SDL_CreateWindow("Dominiks window", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 1024, 768, SDL_WINDOW_SHOWN);
SDL_Renderer* renderer = SDL_CreateSoftwareRenderer(SDL_GetWindowSurface(window));
SDL_Event event;
bool programrunning = true;
int posX = 0;
int posY = 0;
int directionX = 0;
int directionY = 0;
char ch;

void updateScreen(){
    while(programrunning){
        SDL_WaitEvent(&event);
        if(event.type == SDL_QUIT){
            programrunning = false;
        }
        SDL_SetRenderDrawColor(renderer,0,0,0,255);
        SDL_RenderClear(renderer);
        SDL_SetRenderDrawColor(renderer,255,0,0,255);
        SDL_RenderDrawPoint(renderer, posX, posY);
        SDL_UpdateWindowSurface(window);

        if(kbhit()){
            ch = _getch();
            switch(ch){
                case 'W':
                case 'w':
                    directionY = -1;
                    directionX = 0;
                    break;
                case 'A':
                case 'a':
                    directionX = -1;
                    directionY = 0;
                    break;
                case 'S':
                case 's':
                    directionY = 1;
                    directionX = 0;
                    break;
                case 'D':
                case 'd':
                    directionX = 1;
                    directionY = 0;
                    break;
                }
            std::cin.sync();
        }
        std::cout << posX << " " << posY << std::endl;

        posX += directionX;
        posY += directionY;
    }
}

int main(int argc, char **argv){
    SDL_Init(SDL_INIT_EVERYTHING);
    updateScreen();
    return 0;
}

我有两个问题：我如何使它不那么滞后？我如何使移动工作，而我不在控制台？
我试过在循环中编写更少的代码，但它仍然滞后