Serving web requests with ephemeral workers introduces some new problems though. Generally efficiency in this space comes from pooling, reusing connections, multiplexing etc ...

Ie. amortize expensive work over many requests.

Because GC will pause threads while requests are being served, this leads to latency spikes at the higher percentiles.

It introduces a whole distinct type of complexity into operating the server.

The latency of a request to your server is not just caused by the code that is ran to serve that request (which is how people intuitively would think about it), it can be caused by GC pauses that are happening because of the memory pressure caused by previous requests.