It is hard to compare a server side language with a browser side language IMO. But I prefer Javascript /AJAX when fetching data from API or a database in order to reduce the flickering because the whole page do not have have to be rendered / reloaded when updated with new data. I cannot see any speed increase using Go instead of Javascript. Just less flickering…
Both SSR (Server Side Rendering) and CSR (Client Side Rendering) have their benefits. But a mix of them is SSG (Static Site Generation) may be more beneficial. Which means that Go renders the HTML at build time from templates and all dynamic content provided by AJAX (Javascript).
Disclaimer: I have not tested WASM, but as I understand it will it be slower to load initially.