The fastest realization of box-shadow property animation with pseudo-element

fast_box-shadow.css

.box {
  position: relative;
  display: inline-block;
  width: 100px;
  height: 100px;
  background-color: #fff;
  border-radius: 5px;
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.1);
  border-radius: 5px;
  -webkit-transition: all 0.6s cubic-bezier(0.165, 0.84, 0.44, 1);
  transition: all 0.6s cubic-bezier(0.165, 0.84, 0.44, 1);
}

.box:after {
  content: "";
  border-radius: 5px;
  position: absolute;
  z-index: -1;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  box-shadow: 0 5px 15px rgba(0, 0, 0, 0.3);
  opacity: 0;
  -webkit-transition: all 0.6s cubic-bezier(0.165, 0.84, 0.44, 1);
  transition: all 0.6s cubic-bezier(0.165, 0.84, 0.44, 1);
}

.box:hover {
  -webkit-transform: scale(1.25, 1.25);
  transform: scale(1.25, 1.25);
}

.box:hover:after {
    opacity: 1;
}