Dolphin uses Baloo file indexer which causes high CPU and RAM usage causing the device to lag and slow down.
Please simply do a quick web search "Baloo file indexer CPU and RAM usage" - you will find multiple reports around it.
I have faced the same 2 years back, when under Zorin I installed Dolphin. The indexer made my device literally unusable and the CPU fan went crazy, until I manually stop the indexer and remove Dolphin. I'm a bit surprised that no one else here faced this with Dolphin under Zorin.
But still I would not recommend making it default in Zorin.
Using the word "Extension" can cause confusion in this context, as the common use is Gnome Shell Extension.
The folder-color package is a Nautilus Plugin, not a Gnome Extension.
Plugins do supply a feature - that is their purpose. Supplying a plugin is to supply that feature.
This is built in on Nemo File Manager, and the Python and API are matched - resulting in no crashes.
I said the plugin is built in - and this statement is 100% accurate and true, even if it is not integrated into the file manager itself - which I was not saying it was.
Nor is it bundled with it on all distro's; just many.