what is better for performance?

Hi, I am just thinking about that what is better for storeing structured variables in point of view of performance. Is better store structured variables in associative array, for example: $person['first_name'] = 'Karel'; $person['last_name'] = 'Kozlik'; $person['address'] = 'somewhere on Earth'; or in object like this: $person->first_name = 'Karel'; $person->last_name = 'Kozlik'; $person->address = 'somewhere on Earth'; I feel that objects are better for performance, but work with associative arrays is pleasanter for me. May be the diference in performance measurable? (in heavy loaded environment) thanks Karel