NPC's causes server huge server lag in public sessions

Summary

After the Fortnite 39.00 update , all of my AI-heavy islands that use custom npc_behavior scripts combined with NPC Spawner devices began experiencing extreme server instability by causing delays during the elimination process. These islands were 100% stable for over a month prior to 39.00 with no Verse changes on my side.
The delay that occurs when the NPC is eliminated is what causes this lag in maps from what I seen

Please select what you are reporting on:

Unreal Editor for Fortnite

What Type of Bug are you experiencing?

Devices

Steps to Reproduce

Create and Use a NPC definition on an NPC spawner device
Create a verse code that has functions linked to the NPC spawner device
(such as .DamagedEvent() )
Link it to the verse device
Make a PV code, have at least 2+ people in that island and continue eliminating the NPC

Expected Result

When eliminating the NPCs in the long run of a server, no delay should be expected

Observed Result

When eliminating the NPCs in the long run of a server, it will take 2-3 second to actually regsiter and play the animation of the eliminated NPC.

Platform(s)

PC

Island Code

0243-3963-9174

Video

This issue is affecting my map (1316-2698-6957) as well.
Players are reporting the lag can be usually found in servers with at least 60 minutes of session time, which makes me think it could be a garbage collection issue.

2 Likes

Hey any updates to this? @Flak Could you take a look at this, its impacting a lot of islands and a lot of players are frustrated

hi,

just tested on pc , here in UK Europe servers and huge boost the game because its playable

matchmaking and server drop out all gone thanks

THE BANK HEIST [ROGUELIKE] 0243-3963-9174 by ammo - Fortnite

wo

I notice that UObjects steady rise on the server when spawning and destroying a lot of NPC’s with behavior scripts. Memory usage increase on client. Maybe it has something to do with garbage collection. As the problem here starts happening after a certain amount of time and npc’s spawned. Even when using default behavior it has a problem but its less severe.

It 99% has to do with garbage collection.The more enemies spawn / die, the worse it gets.

In my map, if I join a server with more than 100 minutes, chances of it lagging are high, but what makes me think it’s a GC issue is the fact that if you speedrun non-stop for the first 20-30 minutes (therefore making spawn/die way more enemies than in a normal public server) the lag appears before, instead of the classic 100 mins

2 Likes

Any updates to the issue?

1 Like

The team is working on a potential fix for 40.00. The bug reporter will be updated when that is confirmed.

3 Likes

Thank you for the update!

Hey Flak! Any updates so far on this issue. I would like to make sure that theres still a potential fix planned for 40.0 or even earlier. Each update the lag becomes worse in public sessions and now slowly in private…

1 Like

Attaching this video to spread awareness on the severity of the issue:

2 Likes

Having this same issue as well. Thanks for spreading awareness!

Nothing has changed since my last update. This is scheduled to be addressed in 40.00, as long as the potential fix passes testing.

1 Like

Thanks for the update.

Just to stress the urgency, this issue is heavily affecting our roguelike maps with thousands of daily players. Public matchmaking is basically unusable, and asking players to go private isn’t a real solution and doesn’t consistently fix it.

Waiting until 40.00 means a major ongoing impact for both creators and players. If there’s any chance for an earlier fix or temporary workaround, it would really help

2 Likes

FORT-1036153 has been ‘Closed’. We’re unable to reproduce this issue.