There have been a lot of proposals to split the Ninth Circuit, often driven by ideology more than by common sense. There is a sense that the Ninth Circuit is too "liberal" for many conservatives, and particularly for fundamentalist Christians. (That these groups will not accept the possibility that, say, the Fourth Circuit is too "conservative" for people like me bears some careful consideration, but for another time.) For example, some have proposed splitting Nevada and the five northern states off, leaving California, Arizona, and Hawaii as the Ninth Circuit and the remainder in the new Twelfth Circuit. However, California by itself is so big that this would not provide much relief. Splitting California so that part falls in one circuit and part in another is the only purely geographical method that could equalize workloads, but that would make California the only state sitting in multiple appellate circuits.
Actually, that last concern is not strictly true, and points a way toward the beginnings of a solution. Every state is part of two federal Circuit Courts of Appeals: the territorial circuit and the Federal Circuit. The crucial distinction is that the Federal Circuit is not an "option"; instead, all appeals concerning certain subject matters go to the Federal Circuit, and it hears no other kinds of cases. Many of these appeals arise in DC, such as appeals arising from certain federal personnel actions. More to the point here, all appeals that require interpretation of the Patent Act or a patent go to the Federal Circuit, whether they were tried in Chicago, Los Angeles, Boston, or wherever.
Since patents and copyrights have the same Constitutional source, this leads to a possibility that I have not seen considered elsewhere: Send copyright matters to the Federal Circuit, too. Copyright suits are exclusively under federal jurisdiction (28 U.S.C. § 1338), as are patent suits (ditto). Harmonization of copyright law would be a very good thing. At present, there are basically three tiers of appellate circuits in copyright law, based on the frequency of reported copyright decisions in those circuits. The top tier is the Second and Ninth Circuits. This is not surprising; the Second Circuit includes the center of the print publishing industry (New York), and the Ninth Circuit includes the center of film and television (Los Angeles). The second tier is the Sixth and Seventh Circuits. Again, this is not surprising; the music publishing center in Nashville (Sixth Circuit) and financial and information publishing activity in Chicago (Seventh Circuit) explains this well. The third tier is everyone else. (By "tier" I mean only frequency, not "rightness" or "quality" of decisions.)
Unfortunately, there are some rather distressing inconsistencies among the circuits that are unlikely to be resolved by the Supreme Court. Most particularly, the Second and Ninth Circuits have greatly disparate law concerning copyright protection of fictional characters and settings. If a single circuit was responsible for all federal lawsuits arising under Article I, § 8, cl. 8 (the Copyright and Patent Clause), that would at least make the law consistent. The success of the Federal Circuit in resolving many disturbing contradictions in patent law bodes well for such a result. One could even throw trademark suits in, too, but that may be too much, as trademark is also a state-law theory that can be heard in state courts.
Although this by itself would not solve the workload problems in the Ninth Circuit, it would take some of the thorniest problems away and begin to make a dent in the process that just might allow a geographical split to work. Of course, other types of lawsuits could also be assigned to the Federal Circuit; they should, however, probably be limited to lawsuits arising from the narrower of Congress's enumerated powers in Article I, § 8. In any event, this may provide some food for thought.