FastFlags in Roblox serve as the platform’s feature flags, allowing developers to modify how components of the game engine or client operate without needing a client update. They control predefined parts of the code within the Roblox client, enabling users to specify values, activate features, or bypass them entirely.
Though primarily managed online by Roblox, users can manually adjust FastFlags to customize their Roblox experience. Bloxstrap simplifies this process with a user-friendly FastFlag editor tool.
For a comprehensive list of available FastFlags, refer to the scraped FastVariable list or Roblox’s official ClientSettings configuration list.
Important Note:
FastFlags are powerful tools designed for Roblox engineers and can cause issues if misused. Only use the flag list editor if you fully understand each flag’s function. Avoid importing large lists of flags as it might affect stability and functionality. If you encounter problems with Roblox, first try removing any manually configured flags.
Preset FastFlags in Bloxstrap
Bloxstrap includes several preset FastFlags, making it easier to manage these settings.
Exclusive Fullscreen
Relevant flag(s): FFlagHandleAltEnterFullscreenManually
This preset, always active by default, lets you use Direct3D’s exclusive fullscreen mode with Alt + Enter instead of F11. Vulkan always uses exclusive fullscreen. If Roblox flashes black or exits fullscreen when you Alt + Tab, it indicates you are in exclusive fullscreen mode.
Potential issues with Exclusive Fullscreen mode:
- May limit framerate regardless of settings (disabling VSync in GPU settings can help).
- Mouse cursor might not be visible.
- Embedded web browser might not display (exit fullscreen to use it).
DPI Scaling Fixes
Relevant flag(s): DFFlagDisableDPIScale
This preset addresses the drop in Roblox’s graphics quality when screen scaling is above 100%. For example, at 4K resolution with 300% scaling, enabling this flag maintains high visual quality. If performance or battery life is a priority, you might opt not to enable this.
Framerate Limit
Relevant flag(s): DFIntTaskSchedulerTargetFps
By default, Roblox caps the framerate at 60 FPS. This flag lets you adjust that limit. Setting it to zero disables the custom limit, reverting to the standard 60 FPS cap.
Bloxstrap will match the framerate limit to your fastest display. Usually, there’s no need to change this unless you want to disable it. However, increasing the frame rate limit can potentially:
- Increase network latency.
- Cause crashes when teleporting or joining games.
Some games rely on specific frame rates for timing, so it’s best not to set it higher than 240 FPS. If you encounter problems, reset the frame rate limit to 0 to return to the default setting.
Preferred Lighting Technology
Roblox offers various lighting technologies, with each new version generally improving visual quality but potentially impacting performance. Developers might use older techniques to support less powerful hardware. If your hardware permits, you can switch to newer lighting technologies for better visuals.
Important Note: Changing a game’s lighting technology might result in lighting issues (too bright or too dark). If you encounter problems, revert to the game’s default setting.
Escape Menu Version
If you have the new Chrome UI from Roblox, the Version 4 menu is enabled by default. To disable it, import the following JSON configuration into the flag editor:
{
"FFlagEnableInGameMenuChromeABTest2": "False",
"FFlagEnableReportAbuseMenuRoactABTest2": "False"
}
Relevant flag(s): FFlagDisableNewIGMinDUA, FFlagEnableInGameMenuControls
Roblox no longer supports menu versions older than 2023, which may cause some buttons and controls to malfunction, along with minor visual or usability issues.
GUI Hiding
Relevant flag(s): DFIntCanHideGuiGroupId
To use this group-based FastFlag, you must be a member of a Roblox group. Check the flag editor for instructions. For simplicity, you can join the Bloxstrap group. This feature provides keyboard shortcuts to toggle GUI elements:
- Ctrl + Shift + B: Toggles 3D space GUIs (BillboardGuis, SurfaceGuis, etc.)
- Ctrl + Shift + C: Toggles game-defined ScreenGuis
- Ctrl + Shift + G: Toggles Roblox CoreGuis
- Ctrl + Shift + N: Toggles player names and other BillboardGuis above players
Pro Tip: Use Ctrl + Shift + G + C + N for a clean screenshot.
Enabling this also adds a non-functional freecam option to the menu, which can be ignored.
Old Material Textures
Relevant flag(s): FStringPartTexturePackTable2022
Roblox plans to remove this flag, making this option potentially unusable in the future. If you experience issues with old textures, add the following JSON config in the flag editor:
{
"FFlagMSRefactor5": "False"
}
This option restores material textures used before 2022 but may be removed in a future Bloxstrap update.