First render of GeoJsonDataSource takes a long time

I have a react app using webpack. The first render of GeoJsonDataSource takes a few minutes. The geojson only includes about 50 polylines. The following render is faster. Is there a way to make the first render faster?

Or instead of GeoJsonDataSource, is there any other API has better performance?

Here is my webpack setting:

new CopywebpackPlugin({
      patterns: [
          from: 'node_modules/cesium/Build/Cesium',
          to: 'cesium',
    new HtmlTagsPlugin({
      append: false,
      tags: ['cesium/Widgets/widgets.css', 'cesium/Cesium.js'],
    new webpack.DefinePlugin({
      CESIUM_BASE_URL: JSON.stringify('/cesium'),