One side effect of Meltdown/Spectre are CPU microcode (firmware) updates.  For future needs: sysutils/devcpu-data is the port that has the updates for Intel, and cpucontrol(8) is the program you run on DragonFly to add them.

I haven’t used this myself, yet, so I can’t tell you how necessary an immediate update could be – but you will probably want to use it soon.

Update: Newer CPUs might require this sizing change.

Update update: a better explanation of applying microcode updates.  There’s new ones out, too.  (via)