선생님 슬라이드 첫번째사진에서버벅거리는느낌나는건 뭐때문일까요 ..

<!DOCTYPE html>
<html lang="ko">
<head>
    <meta charset="UTF-8">
    <title>c실전연습</title>
    <link rel="stylesheet" href="css/c.css">
</head>
<div class="container">
    <div class="left">
        <header>
            <div class="header-logo">
                <a href="#none"><img src="images/header-logo.png" alt="header-logo"></a>
            </div>
            <div class="navi"></div>
        </header>
    </div>
    <div class="right">
        <div class="slide">
            <div>
                <a href="#none"><img src="images/slider01-c.jpg" alt="slider01"></a>
                <a href="#none"><img src="images/slider02-c.jpg" alt="slider02"></a>
                <a href="#none"><img src="images/slider03-c.jpg" alt="slider03"></a>
            </div>
        </div>
        <div class="items">
            <div class="news"></div>
            <div class="gallery"></div>
            <div class="shortcut"></div>
        </div>
        <footer>
            <div class="copyright">
                상호 :  (주)이스타컴퍼니 | 대표자 : 최종윤 | 개인정보관리책임자 : 이주현 부장 <br>
                사업장주소 : 인천광역시 중구 개항로 6층 (주)이스타컴퍼니   
            </div>
            <div class="sns">
                <div>
                    <a href="#none"><img src="images/sns1.png" alt="facebook"></a>
                    <a href="#none"><img src="images/sns2.png" alt="tiwtter"></a>
                    <a href="#none"><img src="images/sns3.png" alt="instagram"></a>
                </div>
                <div>
                    <select>
                        <option value="">familysite</option>
                        <option value="">여주군청 홈페이지</option>
                        <option value="">한국관광공사</option>
                        <option value="">여행자보험가입</option>
                    </select>
                </div>
            </div>
        </footer>
    </div>
</div>
<body>
    <script src="js/jquery-1.12.4.js"></script>
    <script src="js/custom.js"></script>
</body>
</html>

@charset "UTF-8";
body{
    margin: 0;
    background-color: #fff;
    color: #333333;
}
a{
    list-style: none;
    color: #333333;
}
.container{
    width: 1000px;
    border: 1px solid #000;
    display: flex;
}
.container > div{
}
.left{
    width: 200px;
}
.right{
    width: 800px;
}
header{}
header > div{
}
.header-logo{
    height: 100px;
   
    line-height: 130px;
}
.navi{
    height: 400px;
    border: 1px solid #000;
}


.slide{}
.slide > div{
    border: 1px solid #000;
    height: 350px;
}
.items{
    display: flex;
}
.items > div{
    height: 200px;
    border: 1px solid #000;
}
.news{
    width: 300px;
}
.gallery{
    width: 300px;
}
.shortcut{
    width: 200px;
}
footer{
    display: flex;
}
footer > div{
    height: 100px;

    text-align: center;
}
.copyright{
    width: 800px;
    padding-top: 30px;
    box-sizing: border-box;
    text-align: center;
}
.sns{
    width: 200px;
}
.sns div{
    height: 50px;
    box-sizing: border-box;
}
.sns div:nth-child(1){
    padding-top: 15px;
}
.sns div:nth-child(2){
    padding-top: 10px;
    box-sizing: border-box;
}
/*slide*/
.slide{
    position: relative;
    width: 800px;
    height: 300px;
}
.slide >div{
  
}
.slide >div a{
    font-size: 0;
    width: 2400px;
    position: absolute;
    top: 0;
    left: 0;
    animation: slide 10s linear infinite;
}
.slide >div a:nth-child(1){
    animation-delay: 0s;
}
.slide >div a:nth-child(2){
    animation-delay: 3.5s;
}
.slide >div a:nth-child(3){
    animation-delay: 7s;
}
@keyframes slide{
    0%{
        opacity: 0;
        visibility: hidden;
    }
    5%{
        opacity: 1;
    }
    35%{
        opacity: 1;
    }
    40%{
        opacity: 0;
    }
    100%{
        opacity: 0;
    }
}

선생님 슬라이드 첫번째사진에서버벅거리는느낌나는건 뭐때문일까요. 가로세로는 이해가되는데 페이드인아웃 효과가 젤어렵긴하네요 .. 일단 해봤는데 약간 버벅거리는느낌이있는거같아 첨부해보아요,,

인프런 커뮤니티 질문&답변