You can test it yourself, while you can still find non-AWS regions, and see how they perform comparatively. We're looking at 15%/20% higher Script Times of the default script. 🙃
https://jira.secondlife.com/browse/BUG-229617?focusedCommentId=639234&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-639234
This simple test can be quickly performed with Firestorm.
That comment is from a "duplicate" JIRA, this is the JIRA that Lucia started and stands as the main one. https://jira.secondlife.com/browse/BUG-229611
I was told that all remaining regions are going to be moved to AWS today (hope not, I still have 1 'good' one), so test fast 😋