most of the brexiteers are waiting until they can get a guaranteed blue passport before renewing so this time next year will be a busy period!
But at this time of year renewals are very quick and on another board some one reported a less than a week turnaround a couple of weeks ago.
One thing that I think helps speed the process is completing the application form on-line as HMPO can then start the checks it does before actually getting the physical form back from you