Who is referred to as "Jerome, Jerome the metronome" in regards to playing the piano?

The character referred to as "Jerome, Jerome the metronome" is Lamar, who is a notable character in the film "Gattaca." He uses this nickname to highlight Jerome's precision and consistency, much like a metronome, which is a device used by musicians to mark time at a selected rate of speed. This nickname emphasizes Jerome's role in the world of genetic perfection and his struggles with expectations versus reality, as he is genetically engineered to excel.

Vincent, on the other hand, is the protagonist who embodies the struggle against societal norms and genetic discrimination. Irene and the Director also play important roles in the story but do not have the specific association with this nickname. Lamar's witty reference serves to illustrate both the high standards set by the genetically superior and the societal pressures surrounding those who do not meet those expectations.