In my experience, autopair-mode felt extremely sluggish when a large number of buffers were open (plus, paredit-mode ensures that delimiters will never be unbalanced, unlike autopair-mode ). So, if, like me, you absolutely want to use paredit-mode , and there is nothing more to be done, see this answer . In the elisp snippet there, simply replace slime-repl-mode-map and slime-repl-mode-hook with the appropriate variables for php (most likely php-mode-map and php-mode-hook )
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