Roblox Fast Flags in 2026: the Allowlist, Which Flags Still Work, and What to Use Instead

Tue Oct 20, 2026 12:02 pm

Quick Summary

Fast Flags are now allowlisted. Since September 2025 the Roblox client only honours flags that appear on an official list. Anything else you write into ClientAppSettings.json is read and discarded, not blocked, not punished.
The list is short, roughly 18 flags. They cover level-of-detail distances, texture quality overrides, fullscreen handling, grass draw distance, DPI scaling, and the graphics API selector (Direct3D 11, Vulkan, OpenGL). Performance and networking flags are almost all gone.
Bloxstrap is not banned, but its flag editor is mostly dead weight. Bloxstrap and FishStrap still work as launchers and for their other features. Flags they inject that are not on the allowlist do nothing.
The frame cap moved into Settings. Open the Roblox menu in any experience and use the maximum framerate setting instead of hunting for an unlocker.
Fast Flags are the wrong tool when Roblox stutters. Graphics level, lighting technology, render distance, and a wired connection move more than any flag does.

What the Fast Flag Allowlist actually is

Fast Flags are Roblox's internal toggles. Roblox engineers flip them server-side to roll features out gradually, to A/B test rendering paths, and to switch things off when something breaks. Players found out they could write their own values into ClientAppSettings.json in the local Roblox folder and change how their own client behaved. That worked for years, and tools such as Bloxstrap built a whole settings UI around it.

In September 2025 Roblox replaced the open door with an allowlist. The announcement came from Roblox staff on the Developer Forum, and it is blunt about the mechanism: only flags on the official list are recognised by the client, and any flag you set that is not on the list is simply ignored. Roblox's stated reasons were platform integrity and stability. They pointed at an older thread where creators reported flags being used to cheat, and they noted that in some cases a bad flag could destabilise the client badly enough that a reinstall was needed.

Two details in that announcement matter for anyone reading guides today. First, the list changes. Roblox reserves the right to add or remove flags at any time without warning, and their own post says so in a disclaimer. Second, nothing happens to you for setting a blocked flag. No warning, no ban, no moderation action. The value is dropped.

Source: Allowlist for local client configuration via Fast Flags, Roblox Developer Forum announcement

The allowlist as it stands

The list is short. Here is the whole thing, grouped the way Roblox groups it:

Category	Flags you can still set locally
Geometry	[c]DFIntCSGLevelOfDetailSwitchingDistance[/c], [c]DFIntCSGLevelOfDetailSwitchingDistanceL12[/c], [c]DFIntCSGLevelOfDetailSwitchingDistanceL23[/c], [c]DFIntCSGLevelOfDetailSwitchingDistanceL34[/c]
Rendering	[c]FFlagHandleAltEnterFullscreenManually[/c], [c]DFFlagTextureQualityOverrideEnabled[/c], [c]DFIntTextureQualityOverride[/c], [c]FIntDebugForceMSAASamples[/c], [c]DFFlagDisableDPIScale[/c], [c]FFlagDebugGraphicsPreferD3D11[/c], [c]FFlagDebugSkyGray[/c], [c]DFFlagDebugPauseVoxelizer[/c], [c]DFIntDebugFRMQualityLevelOverride[/c], [c]FIntFRMMaxGrassDistance[/c], [c]FIntFRMMinGrassDistance[/c], [c]FFlagDebugGraphicsPreferVulkan[/c], [c]FFlagDebugGraphicsPreferOpenGL[/c]
User interface	[c]FIntGrassMovementReducedMotionFactor[/c]

Read that rendering row carefully. Of the thirteen rendering flags, the ones that touch performance are the level-of-detail distances, the two texture quality overrides, the grass distance pair, and the graphics API selector. Everything else is a debug toggle, a sky colour, or an anti-aliasing sample override.

Notice what is missing. There is no task scheduler flag, which means no framerate unlock flag. There is no connection MTU flag, no resend buffer flag, no network prediction flag. There is no low memory mode flag and no post-processing disable flag. In other words, the flags people reached for when they wanted more frames or lower ping are exactly the ones that got dropped.

Sources: Roblox Developer Forum announcement and community mirror of the allowlisted FastFlags with default values

Which flags are worth setting in 2026

Only four jobs are still reachable through this list, so be honest about what is on offer.

Force the graphics API. [c]FFlagDebugGraphicsPreferD3D11[/c], [c]FFlagDebugGraphicsPreferVulkan[/c], and [c]FFlagDebugGraphicsPreferOpenGL[/c] pick the renderer. This is the one flag group where a bad driver can genuinely cost you frames, and where switching is worth a try. Results are hardware and driver specific. One independent community benchmark of Arsenal and Evade found Direct3D 11 slightly ahead in both, while Evade ran at a higher average frame rate on Vulkan but with worse percentile numbers, which points at stutter rather than smooth gains.
Drop the level-of-detail switch distances. The four [c]DFIntCSGLevelOfDetailSwitchingDistance[/c] values decide how far away geometry drops to a cheaper model. Lower them and you trade pop-in for frame rate on large, busy maps.
Cap grass draw distance. [c]FIntFRMMaxGrassDistance[/c] and [c]FIntFRMMinGrassDistance[/c] limit how much grass the client renders. Grass is one of the more expensive things in outdoor experiences.
Override texture quality. Set [c]DFFlagTextureQualityOverrideEnabled[/c] to true and then use [c]DFIntTextureQualityOverride[/c] with a numeric value. This is a blunt instrument. A low number blurs every texture in the game, and on lower-end mobile hardware players have reported the stock texture streaming producing unreadable decals and blurry materials with no in-game way to fix it.

Sources: Voidstrap Fast Flags page listing the allowed flags with per-flag notes, community DirectX 11 versus Vulkan benchmark in Arsenal, Evade, and Forest Demo

Bloxstrap, FishStrap, and what the launcher can still do

The launcher itself was never the problem. Bloxstrap and FishStrap are bootstrappers. They write ClientAppSettings.json, set a few environment variables, and launch the official Roblox client. Nothing in that process modifies the client executable.

Roblox staff said on the Developer Forum that Bloxstrap is allowed, and in the same thread said that multi-instance is considered an exploit but that they were not banning for it at the time. That is a deliberate distinction, and it has held for over a year: the bootstrapper is fine, injecting flags that edit game behaviour is not.

What changed is the flag editor. A developer who maintains a public repository of Bloxstrap performance flags opened it with a note that as of the October 2025 update, only a limited allowlist of Fast Flags can be modified locally, and that most performance and networking flags no longer have any effect. A separate troubleshooting write-up reaches the same conclusion from the other direction, saying most cases of a flag that appears to be saving but doing nothing are really the client rejecting flags outside the allowlist.

So the practical answer for 2026: keep Bloxstrap for its launcher features, theme options, and integrations if you use them. Do not expect its Fast Flags tab to do anything meaningful, and do not treat a Bloxstrap config file as a performance solution.

Sources: Roblox staff reply on whether Bloxstrap is allowed, bloxstrap-optimization-flags repository noting most performance flags no longer have an effect, Bloxstrap FastFlag troubleshooting article explaining flags saved but ignored

The frame cap moved into Settings, and that is why the flag died

The reason the framerate flag disappeared is that Roblox replaced it with a real setting. In May 2024 Roblox introduced the maximum framerate setting on Windows, with options for Default, 60, 120, 144, and 240 FPS. Mac support was announced for a later date with no timeline. In the same announcement, Roblox told players to use the in-game setting instead of an external unlocker, because unlockers worked by changing an internal dynamic flag that was never a stable public API and could change without notice.

That sequence explains the whole history. Staff said back in 2024 that they wanted to make good-faith flag flips unnecessary before locking the client down. The framerate setting shipped. The allowlist shipped. The job the flag used to do is now done by a dropdown.

One consequence worth knowing if you script for Roblox: higher client framerates change delta time. Roblox's own example is a part rotating by one degree every [c]PostSimulation[/c] frame, which spins at 60 degrees a second at 60Hz but faster on a 144Hz client and faster still in VR. Anything frame-based should multiply by delta time instead.

Source: Introducing the Maximum Framerate setting, Roblox Developer Forum

What to do instead when Roblox stutters

If you came here for frames, the allowlist is the wrong tool in 2026. Roblox's own support documentation separates lag into three kinds and treats graphics level as the graphics fix.

Check your graphics level first. In any experience, open the menu with the Roblox logo or Esc, go to Settings, and look at the graphics section. Switch Graphics Mode from Automatic to Manual and move the quality slider left for performance or right for visuals. Roblox notes that lower levels reduce visual quality but make the device work less.
Pick a lighting technology deliberately. Third-party settings guides currently recommend ShadowMap over Future as the default and describe Future as costing roughly 15 to 25 percent frame rate in outdoor scenes. Treat that as a rough guide rather than a measurement. If your experience forces a lighting mode in Studio, this setting does nothing for you.
Drop render distance and terrain quality to Medium. Terrain detail mostly matters in open worlds and does little in indoor or obby-style games.
Use a wired connection and open the right ports. Roblox uses UDP 49152 to 65535. Firewalls and antivirus suites that block those ports are one of the most common causes of connection problems, and switching from Wi-Fi to ethernet is the single quickest network test.
Close background apps. Roblox lists system lag, caused by other high-power apps taking resources, as a separate category from graphics lag.

Sources: Roblox Support: Graphics Quality, Roblox Support: How to Reduce Lag and Speed Up Play, Roblox Support: General Connection Problems

FAQ

Will I get banned for using Fast Flags that are not on the allowlist?
No. Roblox's announcement answers this directly: flags not on the allowlist are ignored and no further action is taken against the user. Bloxstrap as a launcher is allowed. What staff flagged as an exploit is multi-instance, though they said they were not banning for it at the time. The risk to your account comes from injected scripts and modified clients, not from a settings file.

Can I get a flag I want added to the allowlist?
Yes, through the official channel. Roblox asks for a feature request in the Engine Features category of the Developer Forum, ideally with a concrete use case. A community thread collected the flags players wanted added, including texture mip flags for low-memory devices and several rendering flags, but Roblox staff replied that some of those were intentionally excluded and that others may be enabled by default eventually. The list is not a menu you can negotiate with, and it can shrink as well as grow.

Why does my graphics look worse than it used to, and is that the allowlist?
Possibly not. Players on low-memory devices, including some iPad and tablet users, have reported materials and decals rendering blurry with no in-game option to restore them. A community feature request documents that with before and after screenshots and links it to texture streaming on devices at or below 4GB of RAM. Since texture flags are restricted, that is Roblox-side behaviour rather than something you broke.

Do Fast Flags still work in Roblox Studio?
Yes. Roblox Studio Fast Flags are not restricted by the allowlist. That matters for developers who used flags to test beta features in-game before they shipped.

Is there any way to raise the frame cap above 240 FPS now?
Not through Fast Flags. The official setting tops out at 240 FPS on Windows. Third-party unlockers still exist and Roblox's position is that they work by changing an internal flag that was never a public API, so they can break without notice.

Should I switch to Vulkan or Direct3D 11?
Test it on your own machine. One community benchmark found Direct3D 11 slightly ahead in average frame rate, with Vulkan higher in one game but with worse low-percentile numbers, which suggests stutter. Your GPU driver version is a bigger variable than the choice itself.

Sources