It was mostly boring. After a surprisingly short time, every conversation I got into felt so hackneyed that it was possible for me to predict the dialogue flow without even thinking.
Not too surprising. As you didn't know anybody, then the majority of the conversations would've been filled with small talk. The nature of small talk is that it's conventional. It's people exchanging lines that have been socially agreed as polite and amicable.
There's no surprise that it would get tiresome after 40 minutes. I mean, that's barely enough time to scratch the surface of one person, let alone a whole party of people.
That's why everyone tends to drink at parties, because it helps them to care less about such things.