The D.C. Circuit has 10% criminal cases. 5 circuits have above 25% criminal cases. The D.C. Circuit has over 30% administrative cases, most circuits have under 10%. The D.C. Circuit has almost no private prisoner cases (cases by prisoners against state officials for violations of rights), while most circuits have over 15%. The D.C. Circuit has over 20% U.S. civil cases (civil cases in which the U.S. is a defendant), while most circuits have under 5%.
Even within those divisions there are relevant distinctions. An appeal from the Board of Immigration Appeals is an "administrative" case, but it's a much simpler matter to resolve, usually, than say a challenge to an EPA regulation. So while the 9th Circuit has almost 30% "administrative cases," each of those are likely much simpler to resolve than each administrative case on the D.C. Circuit's docket (not many people are getting deported from D.C.)
The D.C. Circuit's docket consists very disproportionately of highly complex regulatory appeals, which take much more time than simpler types of cases. These cases are not only often very factually complex, but of a nature that leaves more scope for appellate review. Roughly speaking, when a circuit court reviews the factual findings or discretionary actions of a lower court, it does so deferentially. E.g. an appellate court reviews sentences imposed by a district court only for abuse of discretion. However, a circuit court reviews the legal conclusions of a lower court from scratch (de novo). Regulatory appeals in the D.C. Circuit are much more likely to turn on complex issues of legal interpretation that the appellate court must review from scratch, than on factual disputes that the appellate court need only review for clear error.