Turn off Preview in lower-left corner of control window

I'm running into some issues with video playback stuttering. Forum posts from 2020 or earlier suggested turning off the Preview area (lower-left corner) within the WorshipExtreme Presenter control window to fix that exact issue, and I seem to recall that it helped in my case as well. I'm now on version 2021.2.6, and I can't find any sign of a "Preview Off" feature anywhere.

Based on other forum posts and WE youtube videos, I suspect that the feature "disappeared" sometime between September and November 2020. I use WE for seasonal camp programs, so I haven't used it much in the past six months and didn't notice exactly when this ability went away.

The system I'm currently running WE Presenter on has an Intel i5-4590 processor, 8GB RAM, Intel integrated graphics (will try a dedicated GPU if I can find a low-profile one that fits my case), and an SSD drive. I'm running one control monitor (1024x768 VGA) and one projector output (1920x1080 HDMI). No Stage display or other video outputs. I've checked both the Windows and Linux (Ubuntu Studio 20) versions of WE Presenter 2021.1.14 and 2021.2.6, and neither seem to have the Preview Off feature anymore (a forum post from November 2020 suggests that it's not in the Mac version either). Presenter is nice and responsive on this system -- I just can't quite get smooth 1080p30 video playback.

Is there any way to get this ability back? I have an external monitor that displays the same signal I'm sending to my projector, so I'd really like the option to turn it off and save some processor cycles.

Thanks!!!