Hi there, @davidhlg,
I’d recommend doing it. The answer is unfortunately yes, so long as the processing is happening in the browser. You need to keep the regenerating page open because the process is run through the administrator’s browser session. If you close your browser or lose your connection, it will interrupt the process.
While thinking of a workaround to help you with that, I thought of doing the job in multiple legs. Regenerate Thumbnails, however, doesn’t allow regenerating thumbnails in multiple legs inherently. You hit the regenerate button, and it goes until it’s done. However, you can partially work around this by using their ability to regenerate thumbnails for specific images. You can regenerate images per page (Bulk Select > Regenerate thumbnails), but with 30k images, it might be a bit challenging.
Hope that helps!
