Not good

That is why, the plugin clearly states is for developers and advanced users.
If your site is simple, you can probably configure it yourself, but if it’s more complex in terms of plugins and theme, then you need to manually adjust it’s settings.

There are faqs explaining it, so you just need to take a look how the ignore list works and why your layout may be broken upon activation.
https://www.ads-software.com/plugins/fast-velocity-minify/faq/

This plugin is a tool for developers and advanced users that understand what speed optimization entails. It’s not meant to be install and run on all sites, though it may work for the majority of them to simply install it.