The UK Patent Office has released a commissioned study examining the "economic impact of delays in processing patents." The report (prepared by the consulting company London Economics) suggests that the delays (1) reduce the incentive to innovate; (2) increase the likelihood of filing applications on non-patentable inventions (for the benefit of patent pending status); and (3) the monopoly power held by the owners of non-patentable applications. The estimate of these costs on the world economy is $11.5 billion dollars per year. [Link][Link] The article has a number of major problems, but its bottom line does not seem clearly wrong.
The political motivation behind the study is to push toward greater cooperation between the patent offices in examining co-pending applications.
The bulk of the calculated “costs” are associated with applicants who need a fast-patent-grant. That problem could be largely solved better structuring elective accelerated and deferred examination. In that system, applicants who value a rapid grant would have access to that avenue (for a fee) while others willing to wait could do so.