Too many 304 and 404 nginx responses after upgrading to version 10.8.7

So I recently upgraded gitlab (omnibus installation) from version 8.11 to version 10.8.7. After upgrading, I noticed that the number of requests coming in over nginx increased over 3 fold from before. And a majority of them are the following.

304 Response for the following types of requests (did not have them prior to upgrading)
/ci_environments_status
/xxxx.json?serializer=widget

404 response for the following type
/merge_requests/ci_status

This increases the number of requests almost 4 fold and I think is the reason for the high load and CPU usage. Is this expected behavior? How can it be avoided?