FiveM server lag: how to find the real cause

"The server is lagging" is the most common and least useful sentence on a FiveM Discord. It covers at least four different problems with different causes and fixes. Before buying a bigger machine, which often changes nothing, here is how to find out what is really happening.

1. Start by describing the symptom

Also ask how many players were connected when it happened, and whether it followed an update or a new script. These two questions often narrow the search.

2. Read resmon, the tool that gives the answer

In game, open the console with F8 and type:

resmon 1

A table appears with one line per resource. The column that matters is the execution time in milliseconds: the time the resource uses on each frame on the client, or each tick on the server.

Check the values at rest, with the player standing still. A resource using 3 ms when nothing is happening is looping for no reason, usually a while true without enough wait. Fix or replace it first. These thresholds are practical guides, not official limits.

3. On the server side: ticks

In the server console or in txAdmin, watch the main thread's tick time. If the server runs at 20 ticks per second, it has 50 ms for each tick. When resources exceed this budget, the server falls behind, and players feel it as teleporting.

txAdmin also shows a performance chart. A curve that shoots up at fixed times points to a scheduled task, often a backup or a badly tuned database clean-up.

For a precise measurement, the built-in profiler records a few seconds of activity, which you then analyze in the browser:

profiler record 5
profiler save /tmp/profile.json

4. The usual culprits

• SQL queries in a loop. A script querying the database every tick for every player brings it to its knees as soon as the server fills up.
• Loops without waits. A while true loop with Wait(0) runs on every frame. This is sometimes necessary, but usually not.
• Entities never cleaned up. After a few hours, abandoned vehicles, placed objects and NPCs make the simulation more and more expensive. A clean-up script solves this.
• Heavy custom maps, which mainly weigh on the client and cause stutter when entering an area.
• Badly configured OneSync, or an old mode left on a server with more than 32 players.

5. Is it really the machine?

Connect to the server and look while it is lagging:

htop          # live load and memory
free -h       # available memory and swap used

• One core at 100%, the others idle: FiveM's main thread is saturated. More cores will not help: fix the resource, or choose a CPU with a higher clock speed.
• Memory full and swap in use: the server really is undersized.
• CPU and memory calm, but it still lags: the problem is in the scripts or the database, not the machine.

6. Or the network?

Ask a player who is complaining to run:

ping SERVER_IP
tracert SERVER_IP   # Windows

If latency jumps in bursts while the server is calm, the problem is on the network path. If all players see latency explode at once, consider an attack: see understanding Anti-DDoS protection and our FiveM protection page.

7. The method in five steps

1. Note the exact symptom, the time and the number of connected players.
2. Run resmon 1 and list resources above 2 ms at rest.
3. Check the server load with htop during the incident.
4. Disable the suspect resource and observe: that is the only real proof.
5. If the scripts are clean and the machine is saturated, only then change your plan. See our FiveM server plans.

Server not starting at all? See common FiveM startup errors.

Frequently asked questions