Like the Jaguar version from which it was based, it contains extensive changes to the map geometry for many levels, mainly for performance reasons. Most notable is that a room is kept with a small usage of textures. Maps with large vertical distances also include modifications. However, most of the geometry changes are only present in maps from the three episodes of the original Doom, since these were taken directly from the already-simplified maps used in the Jaguar port; maps taken directly from "
Thy Flesh Consumed" of The Ultimate Doom and Doom II tend to feature very few geometry changes compared to the original versions. There is noticeable slowdown in some of The Ultimate Doom and Final Doom levels, particularly when using the highest difficulty setting.
