Hi,
This is my first time posting on this forum, so please bear with me 
I have tried to find information on this subject all around the Web and on this forum, but haven’t been able to get valuable info on this issue.
I am using the latest version of Cubase (v10.5) on Windows 10 (v1909, fully updated), and the latest version of Autotune Pro (v9.1), and on a high performing computer/setup (RME, i7, 32GB RAM, etc.). This issue has been present since I can remember, i.e. Windows XP/7, Cubase 5 or so, and as old a version of Autotune as well, so this is not related to CPU load or such performance issues with hardware.
So, here is (finally) the issue 
On any track, when the Autotune Pro plugin is loaded, audio playback drops out/mutes for around 1-2 seconds and comes back. Not only does this happen on first plugin load, but it further happens EVERY time the plugin window is opened (that is, while mixing and simply opening the plugin window to adjust settings on a track, the whole audio playback is cut for such time, which is starting to get on me’nerves, if you know what I mean
Though I would understand that Cubase would have to adjust latency of all tracks playing back on loading the Autotune plugin, and that could be the reason for the “audio dropout” (resyncing all tracks to the project overall latency), I cannot understand why this issue happens on EVERY window open of the plugin instance…
This causes issues as well, you will understand, while tracking (if a client so asks to have Autotune on playback while recording), since any time the plugin window is open (to adjust settings) while recording, audio drops out/mutes and recording automatically stops (track arming is disabled).
Thank you so much for your time peeps, and hope this goes well with the forums rules and ways 
–
Antoine