We have hit a new high in open pull requests: 469 today. While we can certainly get more review bandwidth, many of these are old and still open for other reasons. Some are stale because the original authors have become busy and inactive, and some others are stale because the committers are not sure whether the patch would be useful, but have not rejected the patch explicitly. We can cut down the signal to noise ratio by closing pull requests that have been inactive for greater than 30 days, with a nice message. I just checked and this would close ~ half of the pull requests.
For example: "Thank you for creating this pull request. Since this pull request has been inactive for 30 days, we are automatically closing it. Closing the pull request does not remove it from history and will retain all the diff and review comments. If you have the bandwidth and would like to continue pushing this forward, please reopen it. Thanks again!"