I think it depends on the person, it doesn't make us feel cool nor uncool, happy nor unhappy. In general, we think it's good to eat warm dish while it is warm. Besides the texture of noodles with much soup will be changed rapidly and some people hates soup getting cold and soggy noodles. However it doesn't mean polite nor impolite if you eat food fast or slowly. We eat fast when we don't have much time, especially lunch during the work. In other time, wether we eat fast or slowly is depending on the situation, whom we eat with, at least I do so. I'm not sure if I understand your question well for my English. If I understood wrong, please wait for other answers.

In my opinion,I think they will be happier if you slurp their noodles and eat fast.I used to take dinner with Japanese,when they ate noodles,they always acted like that,it's a informal manner for Japanese.