In a new post on his blog Timothy Boronczyk has a recommendation for developers working in PHP with databases that have a "fetch object" method - use it correctly or avoid it all together.
Lately I'm finding a lot of instances of the mysql_fetch_object() function being used in a particular codebase I help maintain. Unfortunately, I've yet to see it used correctly. It always seems to be used to retrieve a stdClass object from a query result where mysql_fetch_array() or mysql_fetch_assoc() would be the more appropriate choice.
Most of his complaint is that, despite pulling out the data as an object, most scripts continue to use it like you would an array, looping over it. There's extra overhead generated from the object creation that could cause issues, especially with large return data sets.
The best advice I can offer is to educate yourself and others how the function should be used so its abuse isn't perpetuated. Then, be cautious when using mysql_fetch_object() correctly and understand the process it follows to create and return an object. If not for yourself, then do it for the kittens.