Hi!
I didn’t find anything about this issue so I assume it is not reported yet.
I experience a delay when using the built-in HC bypass in automation, of about half a second.
This looks like a bug in Cubase 8.5 (please see attachment)
Could you please try to recreate and see if that’s happening to you too before posting a reply? 
Or if this issue is already reported give me a link and kick me off 
Hello,
can you please check the ‘EQ/Filter Transition’ option in the MixConsole?
You find it when clicking on the arrow on the top right of the MixConsole. ‘Soft’ indeed has a delay of 500 ms, ‘quick’ is immediate.
Best,
Hi!
Yes! This solved to problem!
Why does this option exist and why is the default position ‘soft’ ?
Starting to hate Cubase and consider moving to a different DAW because of all those many weird changes they have made from a straightforward program in the days of version 5/6 to a weird mobile application-like with many unwanted features in the 8.5
Thank you anyhow 
Hello,
it’s like this since Cubase 7, IIRC.
It’s made to avoid possible clicks that can occur with sharp changes.
One man’s unwanted feature is another man’s request 