It is easily comprehensible and imaginable by a lay person that a social gathering which induces self focus in a person also leads to his/her divided attention. But what is surprising is that it also leads to impaired memory. A study showed that individuals under situations of scrutiny or social anxiety had problems recollecting names and characteristics of people they met. "Public self consciousness was the crucial determinant of how much evaluation of others affect people."
A good example of this is what happened to my friend who failed his first driving test. When the driving examiner sat beside him, he became self conscious which led to divided attention. Less focus on the environment around him led to his missing a stop sign and thus failing the test. The guy to his much relief passed the next test and drives happily now.
Also children who are under strict srcutiny and constant judgement by their elders become diffident and more self focussed. This ultimatley harms their personality and their social behaviour. I am in much favor of letting people be themselves wherever they are.
While a bit of focus on yourself might help but definitely excessive self-consciousness is big No.
Reference: Self-Consciousness, Public and private Self-Awareness, and Memory in a Social Setting, Kimble et al, The journal of psychology, 119(1), 59-69.