Trying to do a guitar track with my latency set at 64 I found it impossible -sounded more like it was on 2048.  After trying the obvious; reload Sonar, reboot PC, I eventually found that it's due to a track on which I have a simple two-node volume envelope and an EQ envelope turning an instance of FabFilter up and down (once).  That's not right surely?  I have a powerful PC and it copes with a lot more than that on occasions.  Bug? In Sonar or FabFilter?

Strange indeed. I can't imagine why automation itself would increase latency. Well, at least not enough so you'd notice. Are you sure it's the automation? IOW, does the symptom cease when you disable automation reads? 

Sounds like a FabFilter issue not an automation issue.

You are using Pro-Q processing set to Zero latency, right?