SmoothServer

SmoothServer

> Actively maintained for Valheim 1.0. Rebuilt for 1.0.7 on launch day and kept current as patches land; > version 1.x of the mod is in the works. Bugs and ideas: GitHub issues. > > Designed and thought up by Nosferatu from real pain points hit running a co-op server. > Coded using Claude, tested by humans.

Networking and performance tuning for Valheim dedicated servers — and, since 0.3.0, an optional client half in the same DLL.

The server half is the point of the mod and it still needs zero client installs: [General] EnforceClientMod defaults to false, so vanilla players can always join. Install the same package on players' machines as well and you additionally get packet compression, a client send budget and a server-wide shared map.

Installing

Server admins — install into the server's profile (BepInEx/plugins/SmoothServer/). Everything under "Server modules" below starts working immediately; nobody has to install anything. Config file: Nosferatu.SmoothServer.cfg in the server's BepInEx/config/.

Players — install into your own profile only if the server also runs SmoothServer 0.3.0+. [General] Mode is Auto: a dedicated server runs the server half, your game runs the client half. You get compression, the client send budget and the shared map; server-owned settings are pushed to you by the server.

The package contains six DLLs, not one: SmoothServer.dll plus ZstdSharp.dll, System.Memory.dll, System.Buffers.dll, System.Numerics.Vectors.dll and System.Runtime.CompilerServices.Unsafe.dll (the zstd codec and its dependencies — none ship with Valheim or BepInEx). A mod manager handles this; hand-installers must copy all six.

Mods this replaces — uninstall them first

| Uninstall | Replaced by | Where | | --- | --- | --- | | CW_Jesse / BetterNetworking | Compression + SteamRates + SendQueueGuard | server and clients | | Mydayyy / ServerSideMap | SharedMap | server and clients |

Both must go from every machine. If BetterNetworking is still installed, Compression refuses to patch (FAILED(...) in the module summary) and the rest of SmoothServer loads normally — it will not break your server, it just will not compress. SharedMap imports an existing <world>.mod.serversidemap.explored file once on first start, so no exploration is lost.

Server modules

Each module has its own Enabled toggle in its config section.

• Telemetry [Telemetry] — periodic fps / frame-time / ZDO-rate log line. No gameplay effect.
• FrameRate [FrameRate] — raises the dedicated server's Unity frame cap. 60 is a good

default on modern hardware: roughly +4pp of one CPU core for half the tick latency.

• SendCadence [SendCadence] — sends ZDO updates to every peer on a fixed interval

(SendHz, default 20) instead of vanilla's one-peer-per-frame round robin. Scales with player count.

• SendBudget [SendBudget] — the ZDO send-queue high-water mark and minimum chunk size,

exposed as config: HighWaterBytes defaults to 65536 (vanilla 10240), MinChunkBytes to 2048 (same as vanilla). Acts as the fallback when AdaptiveBudget is off.

• CreateBudget [CreateBudget] — objects created per frame, exposed as config (default

matches vanilla, i.e. a no-op until raised).

• PeerTelemetry [PeerTelemetry] — per-peer ping, throughput and Steam send-queue sampling.

No patches; feeds AdaptiveBudget.

• AdaptiveBudget [AdaptiveBudget] — a per-peer send budget from each peer's measured

bandwidth-delay product, clamped, EMA-smoothed, and backed off while Steam's pending byte count says the pipe is congested. A player on fibre next door and one on satellite no longer share one number.

• SteamRates [SteamRates] — raises Steam's SendRateMax (default 1 MB/s).

SendRateMin stays at vanilla on purpose: it is a floor on Steam's own bandwidth estimate, and raising it stops the congestion controller backing off for weak connections.

• SendQueueGuard [SendQueueGuard] — defers, never drops, while a peer's Steam send queue is

backed up, and survives the Steamworks throws that can occur mid-handshake.

• SyncListCache [SyncListCache] — caches the per-peer sector scan in ZDOMan.CreateSyncList

briefly; the filter and sort still run on every send.

• VPOServer [VPOServer] — the server-safe parts of ValheimPerformanceOptimizations (MIT):

WearNTear support caching and a faster ReleaseNearbyZDOS scan.

• AsyncSave [AsyncSave] — pre-sizes the save clone list. Measured on a 136 000-ZDO world,

main-thread autosave stall 67 ms → 47 ms and 78 ms → 45 ms.

• GcThrottle [GcThrottle] — rate-limits Resources.UnloadUnusedAssets on an idle server.
• OwnershipRelease [OwnershipRelease] — shortens the ZDO ownership-release interval from

vanilla's 2 s (default 0.5 s) so objects change hands faster as players move.

• MapSelfTest [MapSelfTest] — headless unit tests for the shared-map codec at load; shows up

as applied PASS in the module summary.

• PriorityLane [PriorityLane] — both ends. Holds this machine's outgoing backlog in a

priority queue instead of letting it pile up inside Steam's own buffer, and hands Steam only about one bandwidth-delay product at a time, latency-critical traffic first. A melee hit no longer waits behind tens of kilobytes of bulk world data: the residual delay drops from the 80–430 ms band to roughly 25 ms. Unmodded clients benefit too — only the send order changes, every byte stays vanilla. Coexists with SendQueueGuard and Compression; the ordering rules that keep it safe (never let a destroy overtake the object it destroys, never promote a message whose target the receiver has not been sent, never cross Compression's handshake) are unit-tested at load.