Slow performance while scrolling through the "Choose pages to export" in Exporting PDF in a large space

Summary

Scrolling through the list of pages to export to PDF when choosing Custom Export, is observed to be slower when using Firefox in compare to using Google Chrome.

Environment

• Internet Explorer
• Firefox
• Confluence 5.8.4

Steps to Reproduce

1. Use Mozilla Firefox
2. Have a space that contains a large number of child pages (tested with 4000 child pages)
3. Go to Space Tools > Content Tools > Export > PDF
4. Choose "Custom Export"
5. Wait until all the pages trees are being loaded
   

Expected Results

The following actions:

1. Scrolling through the list of pages and
2. Checking and unchecking pages

Should not take so much time

Actual Results

The following actions:

1. Scrolling through the list of pages and
2. Checking and unchecking pages

Takes a noticably some amount of time

Notes

1. This issue does not observed in Chrome
2. There is negligible difference when using Chrome vs in Mozilla in Confluence latest version, 5.9.7

Workaround

Use Google Chrome