Excessive memory usage in browser

We've had complaints from readers about the site using excessive memory. The initial report indicated it was occurring in Chrome on articles with comments, but we've had subsequent reports about the issue in Firefox with no specific mention of comments. The common thread seems to be that all of the readers experiencing the issue are using Windows.

Paolo has been able to replicate in Firefox on Windows with and without adverts, but not in Chrome:

Firefox on a Windows:
https://drive.google.com/file/d/139WvAlblK1yPRdsoueLo3FDaK8TUvgSa/view?usp=drive_link

Firefox vs Chrome:
https://drive.google.com/file/d/1pjaQEwJdf9RXKMZTG3vwfDHtUH8058c6/view?usp=drive_link

No adverts:
https://drive.google.com/file/d/1Eog8g-UDGzd8X1_qOSdthsSLzpG7piJS/view?usp=drive_link