Any performance difference between http 304 and 404?

Question

We have a web site that does not have a favourite icon favicon.

Therefore, we get a lot of http 404 errors for the file favicon.ico.

For the functionality of the web site it does not make a difference.

But I was wondering if the system uses more time looking for a file that is not there, rather than returning a 304 not modified?

At max load we have ca. 15,000 concurrent connections across all frontend servers.

Answer 1

No, the performance difference is insignificant - if you don't want to have a favicon, I'd suggest creating a 0-byte /favicon.ico: the logs will stop complaining, and the browsers will behave as if there's no favicon.

Also, you could set a far future Expires header for your favicon - that way, the clients will only request it once, further reducing the load.

Answer 2

In terms of the load the request causes on the server, there is no difference. In terms of network bandwidth, a valid 304 response will be a bit bigger, since you also have to include at least a Date and an Expires or ETag headers in the response.

If the idea is to send a response without content, then I think 204 No Content is more appropriate.

If you are absolutely sure that the web site will never ever have a favicon, you could use a 410 Gone response. That tells the client/browser to don't come back and ask again. It is also more likely to be cached by a proxy server than a 404.