I added a fixme for this some time ago, stating that it's not really important for attr assign in multiple assignment to be fast, but I'd like to circle back now and fix it to have more optimal logic with call site caching and stuff. The charlie library (see JRUBY-2403) appears to hit this path in a few places. It's not likely to be a key source of performance improvement, but it would be one less thing to worry about and for cases where it is being used it will be a lot faster. See compiledAttrAssignAssignment in ASTCompiler and everything it calls.