Final Cut Pro allows for setting the playback quality to "Better Quality" or "Better Performance" (accessed in the "View" menu in the viewer). When using Better Performance FCP uses reduced resolution video during playback - which means that if the FxPlug effect doesn't somehow account for that it can be an inaccurate and misleading preview during playback of unrendered effects (and playback of the effect can appear inconsistent with viewing the effect while paused on a single frame). For example something that uses a Blur can look different (more blurred) during playback than it does while playback is stopped. It's possible to use a Vuo "Get Image Size" node and make a parameter (like the Blur radius parameter in that example) be expressed relative to the image height or width to try to avoid or minimize this problem, but I imagine there could be multiple parts of an effect where it might be required to implement this solution - and it occurred to me to wonder if it might be possible to somehow handle it globally at the FxPlug input level - if the FxPlug API allows the effect to "know" the true (not reduced by Better Performance option) image size and then the effect receives a smaller image size maybe there could be an option for it to somehow adjust internally to that situation... Maybe something to consider