Again though, there was A LOT of Chitauri. And they weren't...detailedly attentive to them as they were to Hulk. Hulk was the BIG cgi of that movie.
I sorta see it as like..the chitauri were just the weekly exams/quizes, but Hulk, that was the final for the class. (yes, I am using college references lol)
the point was, there are plenty of movies that feature CGI characters/character heavily, Hulk was worked on for a very long time, and there were a lot of Chitauri, yes the film had a large budget, but there was still A LOT of things in this movie that other movies, and solo movies didn't and won't have. These things obviously cut the spending, and Hulk needed limmitted time. However, every movie in the MCU probably won't NEED as big of a budget, and I am sure they won't run into monetary issues regarding cgi characters. I wouldn't worry too much about Surtur.
Rock's point, and hell, mine, are that, when Surtur is going to be used, chances are, there is nothing to worry about, regarding cgi