Cubase, Live Input FX, Buffer Latency, LABs?

Samplitude in various incarnations has been my DAW of choice for many years. I generally record and mix with “hardware monitoring” so that latency is effectively zero. And I experience no Lost Asio Buffers. So far.

However, recently I was trying to record vocals with FX on the way in (UAD OWS reverb/re-mic and a couple stereo delays). It sounded amazing! Except that the latency from the audio engine became unusable, and my machine exploded with LABs.

Wondering, for Cubase Pro 10 (or 9.5) users on Windows – particularly with RME hardware:
What are your buffer settings when using FX on live inputs?
What is your latency?
Do you experience any LABs?

Meanwhile, does anyone get any improvement (i.e. shorter latency, fewer problems) using Core Audio/AU on Mac with Cubase, as compared to ASIO/VSTs on Windows 10?

Thanks for any input.