The “Unkown” script is ExperienceChatMain - it’s just not labelled for some reason. I can tell because it’s doing calls to GetEngineFeature and Checking Flags on Heartbeat.
It’s the main cause of lag in our game and even my PC can’t handle it. I’m thinking of disabling chat replication for far away players to try and mitigate this.
This is still a major cause of poor performance in my game. I’m going to be moving to LegacyChat until these issues are resolved.
Also happening quite a-lot in my experience regardless of whether we’re using the legacy chat system or the new one: [🔥 UPDATE ] Police Roleplay Simulator 2 - Roblox
I got Bubblechats disabled and the chat window disabled and I got all this killing my experiences performance. 80% of the heartbeat is ExperienceChatMain:
Hey sorry there hasnt been a response from staff in a while.
We are preparing to roll out an additional set of performance improvements to both text and voice bubbles soon.
Internally we have set up some additional profiling workflows to help assess the impact of voice and voice bubbles in general which will be useful going forward, preventing any future regressions.
For anyone who has reported this before, can you confirm if you are using voice in your games? In our internal findings we find voice to be the common denominator in most cases
Yes. SCP: Roleplay has voice chat servers, but Roblox has the bubble visible even when voice chat is disabled.
Not sure if this would be the cause though since the problem causes a lot of lag in big player servers even with voice chat disabled.
Our game is affected and it does have voice chat enabled, yes. Please let us know when these performance improvements have been rolled out so we can monitor for impact ourselves, and thanks for your response, despite it being a little late. 
My reply here and my own topic, those experiences I develop for, that these screenshots where captured in do not use voice chat and have bubble chat disabled.
Our game does not use the voice chat, and we still have the same issues as outlined in this thread.
Adding on to this, even without VC, when we microprofile we see the huge time taken by the ExperienceChatMain script. Are the changes expected to improve performance on games without VC enabled? Also, is there an ETA staff has on when we can expect these features?
Our experiences currently do not use voice chat, but do have bubble chat enabled.
We do have a few changes that should also optimize non-voice experiences pending. Voice experience will likely see a higher lift.
We do experience this in non-voice enabled experiences, particularly scaling with 100+ users in a server. It’s interesting to note that its not constant, it has “spikes”.
It’s worth noting (and not to demean any of the awesome work ya’ll have been doing), but this is using up significantly more frame time that the rest of our entire game , including rendering.
Any questions you may have, please feel free to get in touch.
Same exact issue for me. I frequently host events that typically attract around 100+ players on a single server. The game still uses the legacy chat system, does not use voice chat or camera, and even with the chat disabled entirely, there are still frequent lag spikes and high usage from the same script.
It’s less of an issue in low player servers, but in larger servers, the performance issues quickly become more apparent, at least in my case.
Our game is effected, voice chat disabled. Of note; the performance degradation only occurs after a long time of being within the experience seemingly (hours) on desktop devices only on high volume servers. Several thousand miniscule __newindex calls on TextLabels for TextStrokeTransparency and TextTransparency per frame causing 120ms lag spikes.
We use a fully custom chat UI using the new TextChatService as a backend. We do not use DisplayBubble; we display bubbles ourselves. The default chat UI is disabled as a whole, which is why this is confusing.
Seems like a bug to me.
This happens in Anarchy Chess - Roblox after mere seconds of being in the game.
Microprofiler dump:
For further testing, I teleported around ~130 players to a blank baseplate (no scripts at all - default settings on chat as well.) FPS stayed around 60-70 and frequently spiked the entire time, severely affected by these two Roblox CoreScripts, CoreScripts/ExperienceChatMain (the script mentioned in this post) and another script PlayerListManager. Voice chat was not enabled in this experiment.
I’ve exported the microprofiler from this experiment, but it’s a bit too large for me to upload here so I haven’t.
Owner of that game here, had to switch to legacy chat (which seemed to around three to four times faster than the alternative of keeping the newer chat), because it kept causing repeated lag spikes that made even people on good computer have noticeable lag (most mobile players were having 10fps lag periods)
And for reference for the staff, we had no vc and it happens randomly for around 10 frames before stopping for a few seconds, and it seems to be more laggy the more people there is in a server
Has lasted for months this. Really hoping for an update.
Can this PLEASE be prioritized, for the love of God?
microprofile-20240615-144431.zip (9.6 MB)
No VC support in our game [ DW REVAMP ] Chech0’s Deltarune RP - Roblox.
The chat alone is causing constant lagspikes. You don’t even have to sit in-game for a while for it to happen, it just instantly starts lagging. We’re literally being punished for using the purported “better” system. This is bordering on unacceptable with how long this has been an issue.
This is severely hampering the user experience for our players on lower-end PCs. I don’t mean to be a jerk, but what is taking so long?!
