Rust FPS Fixes: Building Batching, Faster Map Opening and Culling

Update (Nov 5): confirmed in the November update. The performance work shipped. See the patch notes.

Facepunch spent the days before the November update fixing a long list of Rust building parts that were not batching, which can cost frames around big bases. Other commits from November 2 and 3 make the map open faster and rework how bushes and foundations get culled.

Some of this is merged into the main branch and some is still on its own branch. The November update is due today, but the commits do not say which of these changes are in it, so treat all of it as work in progress with no date. This follows our earlier post on the network LOD and FPS push.

What is batching?

Batching means the game draws many similar objects as one group instead of one at a time. That usually costs the CPU less. A part that fails to batch gets drawn on its own, and in a base with thousands of pieces that can add up.

Building skins that never batched

On November 2, Flavien added a test that checks every building skin mesh can batch. The commit notes that 87 failed. A run of fixes followed:

• Scrap King skin, which was not batching.
• Frontier skin, which was not batching at all.
• Gingerbread skin, the same problem.
• Ramps on every skin. None of them were batching.
• HQM walls, frames and spiral stairs.
• Space station roofs and wall corners.
• Crypt stairs, adobe roof parts, brick roofs, twig roofs and brutalist landings.
• Jungle ramps and stairs, container roof lines and frontier floor details.

The branch was merged into main. The commits give no FPS numbers for these fixes, so we cannot say how much you will gain. Our guess is that bases using these skins and a lot of ramps will see the most help, because those are the parts that were failing.

The map opens faster

Ian Henderson made two changes to the map screen on a branch called map_open_optims. These have real numbers in the commits:

• Monument markers are now built during world setup instead of the first time you open the map. That first open goes from about 19 ms to about 2.7 ms.
• Shop markers only refresh when the shop data changed. Before, every map open copied each shop's sell orders and ran its name through a Steam filter. With 60 shops, the shop refresh goes from about 4.2 ms to about 0.4 ms, and the whole map open goes from about 6.7 ms to about 2.6 ms.

So if you notice a small hitch when you press the map key on a server with a lot of shops, this is aimed at that. We did not see this branch merged into main as of November 3.

Bushes, foundations and shadows

Another fix goes after a delay in the jungle. A cipeaX commit says an earlier version could cause big delays in bushes updating, because all the loaded bushes clogged up a work queue. The new version uses one grid for bushes and one for foundations, with no work queue and no physics. That branch was merged into main.

Dayaan also cut the CPU cost of culling foliage shadows, still on a branch. The commit gives no number.

Base and apartment occlusion

Occlusion means skipping things you cannot see. Jake_Rich optimized player room detection so a player's or a deployable's cached room is only reset when rooms near it get rebuilt. The base occlusion branch was merged into main on November 2. A separate branch redoes occlusion for apartment rooms by checking the player's camera position instead of relying on the occlusion culling system.

Other small wins

• Monument and cargo lights can now show from 2000 meters away at night, and they render through a central system instead of the LOD system. This one is about what you see, not just speed.
• 62 lights in the Outpost caboose had their range cut from 80 to 15 meters, saving about 0.1 ms when you are close.
• Gull groups lost some per-frame raycasts that the commit says "might have been the stutter". More on the birds in our seagulls and crows post.

What it means for players

None of this adds anything new to the game, but it could make big bases and busy servers feel smoother. Most of these numbers are small on their own, and the commits test single systems, not whole play sessions. Your own results will depend on your PC and your server.

FAQ

Will these changes raise my FPS in Rust? They could, mostly around bases using the fixed skins and ramps. The batching commits give no numbers, so we cannot promise a gain.

Why was opening the map slow? The game built monument markers on the first open and refreshed every shop each time. Both are being changed.

Are these fixes in the November update? The commits do not say. Some are in main, and map opening was still on a branch as of November 3. See what we knew before the update.

Sanguine Rust

Sanguine Rust is a PVE server with zombies, bosses and skill levels. We test every Rust build on a test island before moving our islands over, so changes like these get checked first. See what Sanguine Rust is about.

Source: Facepunch commits