web - java selenium setting explicit wait has no effect

Question

I recently used selenium as a simple automation tool, but when I tested it, I felt that WebDriverWait wait = new WebDriverWait(driver,20); had no effect. After I entered the mailbox,
wait.until(ExpectedConditions. presenceOfElementLocated(By.id("_mail_component_68_68"))).click(); //Open the inbox

    wait.until(ExpectedConditions.presenceOfElementLocated(By.xpath("//*[@sign='letter'][1]"))).click();
    这两段代码明明页面已经有这个元素了，为啥还要等一段时间才进行操作，而且等待是时间也不是固定的，是我电脑问题，很头疼啊，演示的时候非常尴尬的等好长时间。
    selenium 用的3.4
    火狐用的5.3

static {System.setProperty("webdriver.firefox.marionette","C:Program Files (x86)Mozilla Firefoxgeckodriver.exe");} //Firefox browser driver

static String url="http://freemail.163.com/"; //The address opened by the browser

public String openEmail(Stream<String> userNameSream,Stream<String> passwordStream) throws Exception {

long startTime=System.currentTimeMillis();   //获取开始时间  
WebDriver driver = new FirefoxDriver();            //启动浏览器
driver.manage().window().maximize();            //最大化浏览器
WebDriverWait wait = new WebDriverWait(driver,20);
driver.get(url);        //打开连接
driver.switchTo().frame("x-URS-iframe");        //定位到iframe框架中
userNameSream.forEach(e -> driver.findElement(By.name("email")).sendKeys(e));                //输入账号
passwordStream.forEach(p -> driver.findElement(By.name("password")).sendKeys(p));                //输入账号
driver.findElement(By.id("dologin")).click();                                                //点击登录
Thread.sleep(3000);
if(driver.getTitle().contains("网易邮箱")){
    wait.until(ExpectedConditions.presenceOfElementLocated(By.id("_mail_component_68_68"))).click();                     //打开收件箱
    wait.until(ExpectedConditions.presenceOfElementLocated(By.xpath("//*[@sign='letter'][1]"))).click();
    return "成功，从程序开始到打开第一封邮件用时"+(System.currentTimeMillis()-startTime)/1000+"秒";
}else{
    try {
    WebElement loginMsg  = driver.findElement(By.className("ferrorhead"));                 
    return loginMsg.getText();
    }catch(Exception e){
        return "出现其他问题";
    }
}

Answer 1

WebDriverWait will not execute click until everything is loaded

Answer 2

I don’t know why, but it solved the problem. I used Firefox and it became faster after switching to Google.