TL;DR: This mod improves Levelers Tower SSE by WilliamSea FPS by a large amount on average with no theoretical downside. If I messed something up you will notice objects not rendering at certain camera angles and locations. FPS improvement due to occlusion planes added via CK so no scripting. There is no reason for the game to render everything in the entire cell and for looking at a wall to tank framerate if the the angle the player is looking happens to render the entire cell in the frame of view. This fixes that.

Project Optimization for Oldrim improved performance in interior cells by adding occlusion planes. Occlusion planes tell the game not to render things behind them more or less. This increases performance, sometimes by a huge amount. It was ported to SSE but the patches for some popular player-made house mods were not ported over, and Levelers Tower itself saw several updates after the original SSE port. I decided to learn more about the Creation Kit and how occlusion planes work by making from scratch this performance patch.

This was heavily inspired by the original Project Optimization Levelers Tower patch. I relied on the ideas from the original mod and tried to build upon it. The original performance patch from Project Optimization skipped multiple cells (Battle Arena, Sitting Room, Display Museum, Great Temple, Mannequin Room, Laboratory) which I have now optimized. There are a few other spots in other cells which I tried to optimize more than the original patch.

I'm still a novice when it comes to modding but I had a lot of time to focus on just Levelers Tower and I think the results are pretty good. The following results are based on my own modded load order.

Basement 1 (Flour Mill): 155 vs 296fps
Basement 2 (Next to smelter looking across entire cell): 190 vs 250
Basement 3 (Entering from display room): 153 vs 302
Battle Arena 1 (Entrance): 233 vs 269
Battle Arena 2 (Corner of room looking across entire cell): 213 vs 221
Display Room 1 (Entrance): 210 vs 295
Garden 1 (Entrance): 195 vs 239
Library 1 (Entrance): 172 vs 265
Library 2 (First floor, looking up across room at central location): 209 vs 267
Living Room (Entrance): 208 vs 249
Mines (Entrance): 156 vs 271
Mines (Dining area across room facing mines): 171 vs 200
Temple (Entrance): 282 vs 286
Torture Room 1 (Entrance): 140 vs 233
Torture Room 2 (At end, room across long cages with flame levers): 199 vs 203

                                                                                                          Extra notes:
The most difficult areas to optimize were the torture room (down the stairs from entrance, and the room across the one with long cages with flame levers). Battle Arena 2 area was hard to optimize due to the layout of the map, but if you're using the map as intended I don't understand why anyone would stand at the extreme corner of the cell on the bleachers. When actually engaging enemies you're not going to be looking at the entire map like that.

You might think it's pointless to boost FPS from 140 to 203 as the minimums in the tower, but I disagree. I have a very good computer  and I got 140 minimum standing still. It can fall to 110 or below that when moving. Frametimes can be improved when draw calls are reduced. Screen tearing is less visible without variable refresh rate (which not everyone has) or vsync (which alone causes noticeable input lag). I also don't use any ENB or very heavy mods. So I think both users with good computers and bad computers can benefit from this mod. Or maybe you can cap FPS and reduce CPU/GPU power usage by making it easier to increase frame rate. I just like it when things are optimized.

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Uhh... I compare texture packs texture by texture and I'm 40,000+ pictures in at this point. Come join the madTL;DR: This mod improves Levelers Tower SSE by