Pros and cons of FileVault?

I have a Macbook Pro Retina early-2015 and that's the only Mac I have Filevault set ON because it's a mobile Mac and could be lost or stolen easier than my Mac Mini desktop. It's more secure than without.

Performance, battery, etc. there may be a slight performance hit, but to be honest I have never felt one. Apps open/close fast, file transfers back and forth to my server are fast, internet is fast, etc.

I forgot to answer your question of "So I guess the question is; is it worth it if you don't really keep sensitive information on your computer?"

My opinion is, yes it's worth it. Remember, macOS has Keychain with passwords of web sites visited and/or credit card information. Safari as well assuming these are enabled in Safari/Preferences/Autofill. One may have some sensitive emails organized with purchases, 3rd party app serial numbers/keys. Also, some 3rd party apps have the serial number/key in their About. Contacts could have sensitive information along with phone numbers.

I was wondering if I should set-up FileVault on my initial MacBook Pro setup. I've heard that it's better to do this on the first setup if you're thinking about using it.

Yes it is.

However, is there a downside to using FileVault in terms of computer performance, battery runtime, etc?

No. None. Zero.

So I guess the question is; is it worth it if you don't really keep sensitive information on your computer?

Since there is no disadvantage to using FV, "worth it" is not a factor. It is likely to become the default in future macOS versions though, so you might as well get used to it now.

More than ten years ago, I thought I would use FileVault or whatever it was called then. It took me minutes to forget the password, so I lost everything and had to start again. Take care.

As the population ages and human memory problems become more common, I think passwords and remembering them could become a widespread problem.