I had the same issue. Very small site with CPTs and the back end of the site slowed down to a crawl when activating this plugin. The front end speed was fine but admin pretty much unusable. Which is a shame because the functionality of the sorting posts is really great.
I purchased the “Product Add On” extension for this. It’s $29. Works well except for a bug on the product listing page with the button. I guess this bug was fixed before but was reintroduced somehow. Still, I just hid it via css and will wait until they fix.
