Significant performance drop in high-computation tasks after update 36.20

[FNC_Julianxd (Julianxd)]

Summary

Since update 36.20, my fluid simulation Verse code shows a drastic TPS regression. Previously, the same setup ran consistently at ~23 TPS, but now it only reaches ~6 TPS, reflecting about a 70% performance loss. This drop appears related to the additional transactional memory overhead introduced by AutoRTFM

Please select what you are reporting on:

Verse

What Type of Bug are you experiencing?

Verse

Steps to Reproduce

1. Create a Verse script with higher computation tasks (like a fluid simulation in my example).

2. Run the setup.

3. Observe the TPS values during execution.

Note: Based on old recordings from July 11, 2025 (before v36.20), the same fluid simulation ran at ~23 TPS. After the update, the identical code now runs at only ~6 TPS. (Video below)

Expected Result

TPS should remain stable and consistent, similar to the pre-36.20 behavior

Observed Result

After 36.20 update, TPS dropped massively from ~23 to ~6 TPS on the same code. This is roughly a 70% performance loss.

Platform(s)

pc

Video

Fluid Simulation (before and after v36.20)

Additional Notes

I suspect the performance loss is caused by the overhead introduced by AutoRTFM (Verse’s transactional memory system). According to Epic’s tech blog (https://www.unrealengine.com/en-US/tech-blog/bringing-verse-transactional-memory-semantics-to-c), every write inside a transaction must be logged so it can be rolled back later, and in internal benchmarks they’ve seen code run up to 4× slower. Since this overhead now also applies in async contexts in order to eventually remove the no_rollback effect, it results in massive TPS drops during high-computation tasks like fluid simulations.

[Bug-Reporter]

FORT-968021 has been created and its status is ‘Unconfirmed’. This is now in a queue to be reproduced and confirmed.

[TheBoyDill (TheBoyDillу)]

I want to add to this report that we ran into computation issues in 2 projects we’re working on and that’s how we came to investigating this more. The fluid simulation example is just a really clear way to show the degradation before and after the update.

We also believe this has contributed significantly to detrimental increase in server lag and degradation in our game Cash Tycoon (1890-7083-7904).

This restriction has severely handicapped our workflow and ability to produce complex verse systems.

[AtAshTag]

I had a similar thing and reported it here

Has something changed with the verse engine causing performance issues ?

Summary I published a map recently a cube io game and everything was fine all the way through testing ect i managed to get the map play tested and this also visually looks good yet now for some reason even with 2 players and very small chain lengths its so bad on performance and i dnt get the issue ? Its like after the last update something has drastically changed with the verse engine and it doesnt run as efficient as it did previously Please select what you are reporting on: Verse What Type …

Didn’t even get acknowledged

Broke the game and its unplayable and all I’m using is MoveTo()

[Flak]

We’ll get someone to take a look.

[NoahUEFN]

It’s so interesting. Almost every single map now has small lag spikes that affect ping after the new season update. Before you could easily e.g. Teleport 20 players+ in the same tick without any ping or tps issues. Now if you do that you get a 200+ ping for a few seconds + the yellow connection marker.

[AtAshTag]

Yes something did drastically change my game went from 25tps under strain to 2-3tps and sometimes complete stop