Now I wonder if this is why my laptop (Dell) is so goddamn annoying too.

LatencyMon does show elevated ISR and DPC max exec times (i.e. reports that for realtime tasks my system is busted), and they're also primarily carried out by CPU0. But it's on the order or 2 ms, not 30 ms.

Still a long time though for interrupts I guess. ACPI.sys taking the lead too, with NDIS.sys being close second, and then pretty much nothing else.