Severe lag spikes when moving the mouse in Studio

In Studio, moving the mouse cursor in the viewport while providing no other mouse inputs causes lag spikes on a consistent period of about once every second. These spikes occur in both play solo mode and in Studio as a whole, and they do not occur unless the mouse is being moved over the 3D viewport.

I provided repro steps at the very bottom of the post.

I made sure to:

  • Disable all my plugins including any local plugins & restart Studio
  • Restart Windows before testing
  • Test in a Baseplate

I timed these spikes and observed the spikes getting more severe the longer the mouse is consistently being moved for (By about 21 seconds, I had counted 21 spikes, but the spikes began taking full seconds which prevented me from making consistent measurements past that).

These spikes appear as large time gaps between data in the microprofiler (the spike is not attributed to any bars in the microprofiler). It appears that the main thread hangs, while some threads like FMOD and RakNet threads continue to run unaffected.

The spikes also only occur if no other mouse input is given. For example, holding mouse button 3 (middle mouse), mouse button 2 (right click), mouse button 1 (left click), or even mouse buttons 4 or 5 (forward/backward in history in web browser, no effect in Studio) causes these spikes to vanish.

Observed Microprofiler gaps during spikes (FPS unlocker enabled):

Microprofiler dump (FPS unlocker enabled):
microprofile-20231121-131703.zip (9.1 MB)

Repro steps

Enabling FPS unlocker makes the spikes significantly more pronounced. They are there even without an FPS unlocker though.

The spikes can be quickly reproduced like so:

  1. Open a baseplate.
  2. Hold a movement key such as D.
  3. Wave the mouse back and forth without pressing any other buttons.
  4. Large lag spikes will be observed.
14 Likes

Thanks for the report! Weā€™ll follow up when thereā€™s any update on the issue.

3 Likes

This is continuously going on so I would suggest fixing it quickly since it would get lots of downtime for Roblox studio users.

4 Likes


This has been happening for a while now.

Iā€™m now experiencing this as well. I first noticed it happening while in Test mode and doing firstperson/shiftlock and then quickly looking around, but it doesnā€™t happen in thirdperson. It seems like it lags whenever the mouse is moving over the viewport as long as you arenā€™t clicking on anything. Very strange, and very aggravating.

2 Likes

Just experienced this today. From some research, it looks like this is related to the mouse input polling rate. Though, when I adjusted the polling rate switch on my gaming mouse, it didnā€™t seem to make a difference.

I also noticed that the camera controls were acting strange and erratic when panning in testing mode.

I was able to apply a temporary fix by switching to a different mouse, but this is not a long-term solution. The mouse worked just fine yesterday, and I did not install any new drivers.

Hopefully a fix will come out for this soon!

2 Likes

Iā€™ve started to encounter this issue in studio test mode. It doesnā€™t seem to occur in solo mode though.

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Something I neglected to mention is that this only happens in testing mode exclusively for me, as well.

1 Like

This has also been happening to me recently after installing a new graphics card. Only happens in one game, and doesnā€™t lag if i hold down a mouse button or keep the mouse still. Only lags when i dont click any mouse buttons while moving.

In this video, i stop lagging whenever i hold down a mouse button, but when i release it my frames drop significantly.

Experience Link: BH - Roblox

2 Likes

Same thing happening here and itā€™s pretty annoying. I canā€™t find any good solutions for it. From an older forum post lowering mouse polling rate below 500Hz helped to the extent of moving the mouse around in studio with losing a lot of FPS, but when playtesting my game in Studio the lag persists and moving my mouse makes FPS go as low as 10ā€¦

Roblox please fix this

1 Like

Hey, I actually experienced this ā€œweirdā€ camera effect as well! (Hopefully the same thing weā€™re both thinking about), for me personally it sometimes felt like either getting stuck or becoming higher sensā€¦ Just not moving where it should have.
I tried switching mouse too, but no luck. It seems on a laptop with a trackpad this issue doesnā€™t persist-

1 Like

Sorry to necro but this issue still persists, any update on this matter? @thirdtakeonit

This issue is likely different to the one I reported.

The behaviour I reported happens consistently at an interval of about once per second and goes away if you click or right click whereas yours happens strictly when you are left clicking and it happens constantly instead of once per second. Your game is also probably doing some raycasts with the mouse so thatā€™s likely related to the lag spikes youā€™re encountering.

This is how the workspace runs when all scripts are disabled:

Not sure if our issues are related but my code isnā€™t the cause. My issue only occurs in studio, and gets worse as more players are added to the local testing. Also the lag stops when i hold any key on my mouse, not just left click.

2 Likes

This has been happening to me for a while as well.

Iā€™ve deleted all my plugins and disabled all plugins Iā€™ve installed, and it doesnt help fix the issue. It goes away on its own sometimes.

1 Like

Can confirm this is happening to me lately as well, for some weird reason its only specific to Team test and Local Server instances.

3 Likes

Particularly nasty case here:

I tried shutting off my pc as well, didnt make a difference.

Iā€™ve noticed Iā€™m getting framerate drops in studio when moving the mouse as well

Can confirm this issue is happening to me. On my M1 Max, FPS drops consistently while moving the mouse. It seems to improve when closing any docked windows in Studio. On my Windows desktop, there is no issue. Iā€™ve been trying to debug my game for the past hour looking for performance issues - it turns out this is on Robloxā€™s end.

Interesting to note: Holding down left or right click makes this issue not happen while moving the mouse:

1 Like