Java devs saw that "abc" + "def" involved expensive String concatenation, so as a performance improvement they pro-actively, and effectively manually, changed t

Java devs saw that "abc" + "def" involved expensive String concatenation, so as a performance improvement they pro-actively, and effectively manually, changed to use explicit StringBuffer concatenations. When the compiler switched to generate StringBuilder (unsynchronized) concatenations for "abc" + "def" nobody benefited, because they had already changed to use StringBuffer (synchronized). Now they had to go an undo all of their hard, manual, optimization work. I feel like the same would/might play out here.