I know for a fact bloom is quite slow on mobile devices because of the tiles GPUs. This is because it adds quite some draw calls.
Haven’t seen a huge difference on desktop however. What Unity version and resolution are you running?
Sorry, totally looked over that.
Update to the latest 2020 lts (and maybe try 2021 lts) to see if it gets improved.
Otherwise there isn’t much to do with the native PP stack I think. Then you need to look into custom/3rd party solutions