[LAU] dbus security update slows down DSP?

Hi all, Ubuntu popped up a security update this morning for dbus, which I installed, then rebooted. Now, audio processing in SuperCollider takes about twice as much of Jack's duty cycle as it did before. There aren't any relevant changes in the SC code base between yesterday and today. The only thing that changed since yesterday was the update. I'm not sure how to revert, as a test or longer-term measure. I found "Force version" in synaptic but backing up a version for libdbus-1-3 and libdbus-1-dev will uninstall a ton of other packages, including jack2 (oops!). The new dbus version is 1.4.18-ubuntu1.3, previous was 1.1. It's not catastrophic- I was running well below my CPU's capacity before. But it's not optimal, so if there's a way to adjust, I'd like to try. Thanks, hjh