Shooting lag when back button focusing

[ptao]

I just got an X-Pro2 (with the 23mm/2 lens) and I'm noticing some strange lag when shooting. When shooting as follows:

* Manual focus

* Manual exposure (aperature, shutter speed and ISO)

* Instant AF set to AF-C

I'm noticing two sources of lag:

1. When back button focusing (AF-L is held down), there's a lag when half-pressing the shutter as it locks focus. Is there anyway to disable this? I don't want the focus to be locked while back button focusing, regardless of if the shutter is half-pressed or not... This makes AF-C via back-button focusing a lot slower than AF-C mode, which makes back button focusing pretty unusable.

2. Using the ERF while its zoomed in to the focus point, there's a lag when the shutter gets half-pressed. Strangely, this lag doesn't seem to happen (or is much shorter) when the ERF is displaying the full frame or when using the OVF or EVF.

Basically, I'd like a shutter half press to do absolutely nothing when in using manual focus and manual exposure. Are there any other settings I need to configure?

[cdngrrl71]

I’m seeing this message in 2022 and experiencing the same lag on my XT4 when using manual focus with back button AF-C turned on. No solutions to be had from anyone yet?

[Perplexed]

I've used back button focus on Nikon cameras for over a decade, but I abandoned it on my X-Pro2 because the AF-L button is in an awkward position.  Maybe Nikon ergonomics are too firmly ingrained in me.