offtopic: The eszett strictly speaking was a ligature for ‘sz’, which Hungarian orthography kinda preserved while for German the separated version is ‘ss’, and there’s plenty of such stuff in nature.
In most programming languages, case-insensitive string compare without specifying the culture became deprecated. It should imo only be used for fuzzy searching doubles, which you probably will do with ToUpper on all four performance reasons, or maybe some UI validation.