Hi there,
with every update to the Theme we generally make performance improvements. The latest 3.0 version if you switch the Customizer > General > Structure to Flexbox makes significant reductions to the Themes CSS. So any changes to site performance would not be related to the Theme updates.
If you want to share a link to your site i would be happy to take a look to see if there are any noticeable issues.
One thing to consider when making updates is to ensure you clear and plugin and server caches and any CDN Caches to make sure old code has not been cached.