To me it sounds like it's time for you to get to know Elixir's (Phoenix's) LiveView. It does this even better and you barely write any JS at all.
People are doing genuinely hugely impressive production-grade work there, and I am currently looking at a SigNoz dashboard while >200 users are frantically clicking on dozens of places in our UI (contains many reactive bits); our code is nowhere near optimal and we very rarely get >150ms response times, most are 20-50ms, and we're talking some quite tame machines (2 of them) with 8GB RAM and 2 CPU cores... and even then 90% - 99% of the time is spent waiting on the database.