json_decode all the array values of an php array

I have an array similar to:

[ "id" => "90bbc6f8"
  "user_id" => "7a88a06f"
  "country" => "Greece"
  "region" => null
  "users" => "[]"
  "emails" => "[]"
]

but having hundreds of values, I need to decode the arrays like “users” and “mails”, is there a way to apply json_decode to the values without going through foreach loop? paying attention to the performance