[jrochkind1]

> each `render` call reads the partial off disk, parses it, and executes it

I think it does not do that in 'production' settings, but I'm not sure. I know it does less touching of disk and parsing in production mode, it doens't do all that you mention (that's what the `cache_template_loading` setting controls) -- but I'm not sure it does none of any of that, it may still do things that conceivably seem like they oughta be be cached, not sure.

In default "development" mode settings -- yes, partial template is definitely much slowed down by going to disk and parsing on every request and/or every invocation.

[pjungwir]

I just re-tested on Ruby 3 & Rails 7, and even in development it no longer minds if I rename the erb file in the middle of iterating---so that's an improvement for sure!

I found a Rails issue tracking partial performance in a loop (https://github.com/rails/rails/issues/41452), and it looks like they are still working on improvements. No activity since May though.