After further investigation, it seems this is indeed a separate item, so I am reviving it and changing the status to "Approved".
Posted on:19 Jan 2018 16:13
As we discussed in the support ticket, there is already logged a task to improve the performance when deleting paragraphs. The implementation of this task should improve the performance in this case as well. Thus, I am closing this item. The other one is available at https://feedback.telerik.com/Project/143/Feedback/Details/179146