Plotly.js page render is super slow with 10 charts in DOM. firefox freezes. whats wrong?

I am getting super slow page loads (~10s on chrome, ~15 using firefox) when rendering a page with 10 Plotly charts (lines and bars) with very few data points on each chart (<100 per chart). The page loads plotly from the cdn.

I’m not getting any errors, and my js code runs in ~300ms without errors (i used console.log() with timestamps). there is no network activity whilst waiting for the charts to render.

Am I doing something wrong?

The charts are rendered using a loop which calls a function with different parameters:

ajax call:

  method: "GET",
  url: '/app/api/dashboard/data',
  success: function(payload){
    console.log('starting bal hist')
    var bal_hist = JSON.parse(payload.balance_history);
    balanceHistoryChart(elementID='balanceHistory', data=bal_hist);
    console.log('ending bal hist')

    var data = JSON.parse(payload.aggregated);
    data = {
      object.value_date = new Date(object.value_date);
      return object

    var allCategories = => x.category);
    var categories = new Set(allCategories);
    console.log('starting loop')
    for (var category of categories){
      var chartID = category.toLowerCase().replace(' ','_') + '_chart';
      console.log('starting catChart')
      catChart(elementID=chartID, category=category, data=data)
      console.log('ending catChart')
    console.log('end loop')
  error: function(error_data){

function that creates the plotly charts:

function catChart(elementID, category, data) {
  let filterForCat = data.filter(obj => obj.category === category);

  let dates = {
    return obj.value_date
  let weeklyTotal = {
    return obj.weekly_total
  let movingAv = {
    return obj.moving_av

  var movingAvSeries = {
    type: "scatter",
    mode: "lines",
    name: '4-week average',
    x: dates,
    y: movingAv,
    line: {color: 'green'}

  var weeklyTotalSeries = {
    type: "bar",
    name: 'weekly totals',
    x: dates,
    y: weeklyTotal,
    line: {color: 'red'}

  var layout = {
    showlegend: false,
    title: false,
    margin: {
      l: 30,
      r: 20,
      b: 20,
      t: 20,
      pad: 5

  var data = [ movingAvSeries, weeklyTotalSeries ];

  var config = {
    responsive: true,
    displayModeBar: false,


Did you try to render them in time when they are at display?
Here is a link explaining how to do that: How to Render Plotly Plots in Order ~ Random Problems