Query Question (one group by vs two separate)

I'm asking this as a more general question on which will perform better.
I'm trying to get a set of comments and their score/rankings from two
tables.

*comments*
cid (integer, primary key)
title
body

*comment_ratings*
cid (integer, primary key)
uid (integer, primary key)
score

*Option 1* (Single group by query)
select c.cid,c.title,c.body,coalsece(sum(r.score),0) as score
from comments c left outer join comment_ratings r on c.cid = r.cid
group by c.cid,c.title,c.body;

*Option 2* (Two simple queries)
select cid,title,body from comments;
select cid,sum(score) from comment_ratings;

I know that in general you always want to keep the number of queries to a
minimum and that Option 1 is the most logical/preferred way to proceed.
However, I've greatly simplified Option 1. In practice I'm going to be
pulling a lot more columns and will be inner joining to additional tables.
*So my real question is whether having a lot of items in the group by clause
will have an adverse effect on performance.*

Thanks in advance,
Jonathon