Sudden spike in Server CPU Time dominated by WaitingHybridScriptsJob in main lobby since 2025-08-29 08:30 CEST (06:30 UTC)

Bug Reports Engine Bugs
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1

Experience: https://www.roblox.com/games/14567590300/BATHE-DA-BABY
Affected place: Main lobby (root place)
Unaffected place: Pro Lobby (sub-place) - performance normal

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What happens:
Starting around 08:30 CEST (06:30 UTC) on 2025-08-29, Server CPU Time in the main lobby jumped and stayed high. The average over the last 24h is ~65.844 ms (+575%), with peaks ~150–180 ms. The breakdown is dominated by WaitingHybridScriptsJob. Players report severe lag; ping spikes to over 5 seconds, with timers freezing and general unplayability.

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Why this looks like a platform/engine issue:

  • No deploys from our side since 2025-08-04. Timeline shows no version changes near the spike.
  • Only the main lobby is affected. Our Pro Lobby servers remain normal under similar load.

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System information:

  • Client OS/hardware appears irrelevant: symptoms are server-side and widely reported.

Impact:

  • Severe lag complaints: players report leaving due to unplayable stutter in the main lobby.

Repro Steps:
There aren’t any known reproduction steps yet: we are still investigating. The issue is reported by our community, with symptoms including ping spiking over 5 seconds and timers freezing in public main-lobby servers.

Expected behavior

  • Server CPU Time should match historical levels (pre-Aug-29) without WaitingHybridScriptsJob dominating.
  • Main lobby performance should match Pro Lobby as before.

A private message is associated with this bug report

2

Hello, I’m investigating this for you and I’m curious if you’re still seeing this today - I did a spot check of RCC performance in your lobby and I don’t see any spikes in WaitingHybridScriptsJob - the worst performance I saw was about .12 ms.

Can I ask a few questions about how frequent this is? Do you see this scale up as the number of players join the lobby? The place I sampled had about 33 players/50.

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3

Hey newtonmetre,
This is a singular incident with no clear or explainable cause. It resulted in a decline in player experience and has affected the game for ~ 1.5 days, leading to numerous lag complaints from our community.

In my opinion, the only area worth investigating is whether a Roblox change during that time may have caused it, and how such an issue could be prevented in the future.

As you can see from the report there were no updates in our game for almost a month and it suddenly started spiking, it also fixed by itself, it lasted around 1.5 days

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There is no repro or ongoing issue.

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4

Thanks. I will see if there was a flag flip/revert around this time period that could have caused this.

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