Performance issues rendering items

The description says it can handle over 100K items without any performance issues.
I want to display the files in a directory but only the first 3 rows render and it seems to freeze. After waiting a while the other rows get rendered as well.

ember: 3.15.1.
ember-table: 2.2.3

Using the snippet below I can see the log going in the console but only the first 3 rows render initially.

<EmberTable as |t|>
  <t.head @columns={{columns}} />
  <t.body @rows={{rows.fsDirectory}} as |b|>
    <b.row as |r|>
      <r.cell as |cellValue columnValue rowValue cellMeta columnMeta rowMeta|>
         {{log "cellvalue: " cellValue}}
         {{cellValue}}
      </r.cell>
    </b.row>
  </t.body>
</EmberTable>

Start by reproducing the issue with the provided EmberTable snippet, using the t.body entry point and rows.fsDirectory with a large directory dataset. Compare the initial rendering behavior against the claimed ability to handle over 100K items; done means the rows render without the reported freeze or prolonged delay.