The idea of a symbol is that one does only do a lookup when the symbol is read. During execution the symbol is not read again. After reading the symbol is a ref

The idea of a symbol is that one does only do a lookup when the symbol is read. During execution the symbol is not read again. After reading the symbol is a reference to a symbol object in memory. That's why early Lisp has symbols for identifiers and not strings. Early on the data structure to find or intern a symbol might have been not very efficient, but finding a symbol was thought to be done mostly at read time. Lisp then used a memory image which was loaded on startup (and possibly written on exit) - which contained the pre-interned symbols.