Here's a first, basic test using webpagetest.org, running on Firefox Desktop from the USA.
Full report: https://www.webpagetest.org/result/190924_JQ_ecc07edee2514e77327a3c4955d02038/
Full report: https://www.webpagetest.org/result/190924_Y3_c4af9e06acdff24bcca517fe24e854ce/
|Full Loading Time
Quick analysis based on this simple test: overall performance don't seem to change much. Next is a bit slower to load overall, but starts rendering much earlier (as is expected, since the rendering happens on the client side). Byte size goes up a little, and we might want to look into that and make the JS bundles smaller.
This is a pretty reassuring test as it shows that there is nothing to be concerned about in the major data points: time to load, requests and bytes for Translate.Next are all within acceptable range from Current.
I'll still perform more advanced testing later on.