In our case, we’re using the blade-icons package with a couple different icon sets. We needed to run wp acorn icons:cache and the performance issues were solved 
@Twansparant @monokai have y’all had any luck digging deeper into the source of your issue?
If you aren’t using blade-icons, are you using another package that might have registered a command that would allow things to be cached? You can check by running wp acorn and looking at the list of commands