Ember load performance in IE 11

We have an ember app that loads much slower in IE 11 than in Chrome. This is causing ember tests to take a long time to start and run, impacting load times in production.

The IE dev tools UI Responsiveness shows the primary issue is the script evaluation of vendor.js. vendor.js script evaluation is taking:

• IE: 30s, Chrome: 4s (Loaded from 'ember server')
• IE: 30s, Chrome: 4s (Loaded during 'ember test')
• IE: 04s, Chrome: .5s (Loaded from 'ember server -prod')

We created a new app using ember 2.16.x. vendor.js script evaluation is taking: - IE: 4s, Chrome: .5s (Loaded from 'ember server') - IE: 4s, Chrome: .5s (Loaded during 'ember test') - IE: .3s, Chrome .3s (Loaded from 'ember server -prod')

Other notes:

• Network time is not an issue.
• Once the app is loaded, it performs fine.
• config/target.js is set for 'IE 11' and 'last 3 Chrome versions'

What can be done to improve the vendor.js script evaluation performance in IE 11?