large-table-row-height-change-with-collapsed-border.html

<!DOCTYPE html>
<body>
<script src="../resources/runner.js"></script>
<style>td { border: 1px solid blue }</style>
<script>
function createTable(rows, columns) {
    var table = document.createElement("TABLE");
    // Collapsing border is not necessary to see the slowness
    // but it makes the painting phase ~2x slower.
    table.style.borderCollapse = "collapse";
    for (var i = 0; i < rows; ++i) {
        var tr = document.createElement("TR");
        for (var j = 0; j < columns; ++j) {
            var td = document.createElement("TD");
            tr.appendChild(td);
        }
        table.appendChild(tr);
    }
    return table;
}

var table = createTable(400, 400);
document.body.appendChild(table);

var y = 0;
PerfTestRunner.measureFrameTime({
    run: function() {
        table.childNodes[y].style.height = '20px';
        y++;
    },
});
</script>
</body>

chromium/third_party/blink/perf_tests/mutation/large-table-row-height-change-with-collapsed-border.html