MacOS Mojave, VirtualBox 5.2.20, using with Vagrant 2.2.0 and guest OS Ubuntu 16.04
Since upgrading to 5.2.20 (I don't remember previous version, but not that far behind), I'm intermittently running into high CPU usage on my vagrant box after my Mac wakes from sleep. VirtualBox had been performing fine on Mojave, this has just started happening since 5.2.20. When I first launch the guest, there's no problem. Close my MacBook or otherwise let it go into sleep mode for a while, come back, and often once I wake the Mac the guest will start using high CPU, enough to trigger the fan, which is pretty rare on my MacBook. It doesn't happen every time, and doesn't seem to happen if the MacBook has only been in sleep mode for a while (I'm guessing it's actually hibernate/safe sleep that triggers the behavior). If I check the process list on the guest, nothing running is utilizing high CPU.
Two co-workers just got brand new Macs with Mojave and did clean installs of VirtualBox and Vagrant and are also running into the problem, so it's unrelated to upgrading from an older version.
I'll see if I can grab a log next time it happens (which should be after I head home from work today), but note that any logs can't be from a quick round of start-hit error-shutdown-logs since the problem only happens when it's been running at least long enough for the host to have entered safe sleep.