Olga Plümacher (1839–1895) published a book entitled Der Pessimismus in Vergangenheit und Gegenwart in 1884. It was an influential book: Nietzsche owned a copy (as did Sam Beckett), and there are clear cases where Nietzsche borrowed phraseology from Plümacher.

Plümacher specifies philosophical pessimism as comprising two propositions: ‘The sum of displeasure outweighs the sum of pleasure’ and ‘Consequently the non-being of the world would be better than its being’.

Plümacher cites Schopenhauer as the first proponent of this position, and Eduard von Hartmann as the thinker who has developed it to its fullest potential. She heavily criticizes Schopenhauer in many respects, not for being a pessimist, but rather for not achieving as good a pessimism as he might have done, on the following major grounds: that his account of pleasure as merely privative is implausible, that he has a confused account of individuation, that his retention of a Christian notion of guilt is gratuitous, that he lapses into the self-pitying subjectivity of the condition she calls Weltschmerz, and that his philosophy leads to quietism, and is thus inferior to von Hartmann’s combination of pessimism and optimism, which allows for social progress.

From Abstract : Worse than the best possible pessimism? Olga Plümacher’s critique of Schopenhauer, by Christopher Janaway

https://www.tandfonline.com/doi/full/10.1080/09608788.2021.1881441

Google Books:

Der Pessimismus in Vergangenheit und Gegenwart, Geschichtliches und Kritisches, by Olga Plümacher · 1884

https://www.google.com/books/edition/Der_Pessimismus_in_Vergangenheit_und_Geg/se2FvG44qZQC?hl=en&gbpv=0