Optimize Server Performance

Fix lag, reduce desync, and optimize your Valheim dedicated server. Covers zones, instances, network tuning, and building limits.

Valheim servers can experience lag and desync, especially with many players, large builds, or lots of mods. Understanding how the game works under the hood helps you diagnose and fix performance issues.

How Valheim's Zone System Works

Valheim's world is divided into 64m x 64m zones. The server loads and unloads zones dynamically around each player:

Range	Size	What's Loaded
Active zones	3x3	Creatures move, AI runs, spawners activate
Loaded zones	5x5	Objects, terrain, and buildings are in memory
Generated zones	9x9	Locations and vegetation pre-generated

The critical insight: Valheim is not fully server-authoritative. The first player to enter an area becomes the "zone host" for that area's physics and AI. If that player has a weak PC or poor connection, everyone in that area experiences lag.

This means:

Players spread across the map = more zones loaded = more server work
Each player's hardware quality affects the experience for others nearby
Large builds create many objects (instances) that must be synced across the network

The Instance Problem

Every placed object in Valheim is an instance — building pieces, terrain modifications, dropped items, creatures, torches. Press F2 in-game to see your current instance count.

Instance Thresholds

Instance Count	Performance Impact
Under 8,000	Smooth gameplay
8,000–10,000	Stuttering begins
12,000+	Significant lag on most hardware
15,000+	Severe performance drops, physics glitches

What Creates the Most Instances

Torches and campfires — each creates multiple instances plus smoke particles
Terrain modifications — every pickaxe/hoe action creates a permanent object
Tamed animals and crops — each has AI or growth logic
Dropped items — unpicked loot on the ground
Glass building pieces — reflections add rendering overhead

Reading the F2 Network Stats

Press F2 to see the debug overlay:

Stat	What It Means
Instances	Total tracked objects loaded around you — the primary performance metric
send_queue	Bytes waiting to be sent. If climbing, your client is generating data faster than the network can handle
recv_queue	Bytes waiting to be processed. Growing recv_queue means data is arriving faster than your client can process
Ping	Round-trip time to the server in ms. Under 100ms is good

Diagnosis: If instances are high (8,000+) and send_queue is growing, you're in an area that's overwhelming the network. Reduce building complexity or use optterrain.

Fix Terrain Lag with optterrain

Old terrain modifications (from before patch 0.150.3) store each individual pickaxe/hoe action as a separate object. The optterrain command converts these to the new system that stores just the end result.

Open the console

Press F5.

Travel to the laggy area

Run the command

optterrain

This converts terrain within ~150 meters. Check your F2 instance count before and after — reductions from 17,000 to 9,000 have been reported.

⚠️ Warning: Back up your world before using optterrain. It can occasionally warp terrain near existing buildings.

Scheduled Restarts

Valheim servers accumulate memory over time. Regular restarts are the single most effective performance fix.

Go to Schedules in the sidebar and create a daily restart during off-peak hours. See Scheduled Restarts.

Server Type	Recommended Frequency
Small (1–5 players)	Once daily
Medium (5–10 players)	Once or twice daily
Large (10+ players)	Every 8–12 hours
Heavily modded	Every 6–8 hours

Reduce Build Complexity

The most impactful optimization:

Keep bases compact — fewer building pieces means fewer instances
Limit torches and fires — each one creates particles and instances
Avoid excessive terraforming — every terrain modification is permanent
Pick up dropped items — loot on the ground counts as instances
Consolidate bases — one large base is better than many scattered ones

Mod Optimization

Install BetterNetworking

The BetterNetworking mod optimizes network traffic between server and clients, reducing desync. Install through the Mods panel in the sidebar.

Remove Unused Mods

Each mod adds processing overhead. Only keep mods you actively use.

Check Mod Compatibility

Outdated mods cause lag spikes and crashes. Check Thunderstore for update status after game patches.

Crossplay Overhead

If all your players use Steam, disabling crossplay removes PlayFab relay overhead:

Go to Startup, find the Crossplay toggle, and disable it. Restart your server.

Server Hardware Guidelines

RAM

Players	Vanilla	Modded
1–5	2–3 GB	4–5 GB
5–10	4–6 GB	6–8 GB
10+	6–8 GB	8–12 GB

CPU

Valheim relies heavily on single-thread performance. Higher clock speed per core matters more than core count because physics runs on one thread.

Network Bandwidth

Players	Minimum Upload
1–5	5 Mbps
5–10	10–15 Mbps
10+	20+ Mbps

Dealing with Desync

Desync happens when a player's client falls out of sync with the server but stays connected. Symptoms:

Chests take 10–30 seconds to open
Other players appear frozen or teleporting
Actions don't register

Fix: The affected player should disconnect and reconnect. If it happens frequently, check:

The zone host's hardware and connection quality
Instance count in the problem area
Whether BetterNetworking mod is installed

If you need help, join our Discord.

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