Engine settings

Tweak how Roblox renders, manage Fast Flags by hand, and catch mistakes before you launch.

Roblox exposes a set of internal switches called Fast Flags. Roblox engineers use them to roll out features without shipping a full update, but they can also be set locally, and a few of them control things players genuinely want to change — anti-aliasing, texture quality, and whether display scaling degrades the image.

Where it lives. Settings → Engine Settings. The page is sometimes called Fast Flags in older builds.

Master switch

Allow Agentstrap to manage Fast Flags is on by default. Turning it off means nothing configured on this page is applied to Roblox — the file is still written to your Modifications folder, it's just never copied into the Roblox install.

Rendering presets

Anti-aliasing quality (MSAA)

Option	Effect
Automatic	Roblox picks its own anti-aliasing level. This is the default.
1x	No multi-sample anti-aliasing. Fastest, but edges look jagged.
2x	Moderate smoothing.
4x	Best edge quality, highest GPU cost.

Texture quality

Option	Effect
Automatic	Roblox picks its own texture quality.
Level 0 (Lowest)	Lowest memory usage and fastest texture uploads. Blurry textures.
Level 1	Low.
Level 2	High.
Level 3 (Highest)	Best looking, most memory.

Preserve rendering quality with display scaling

When your Windows display scaling is above 100%, Roblox reduces its rendering resolution to match. Enabling this prevents that, so the game stays sharp on a high-DPI display.

Exclusive fullscreen is always on. Roblox normally fullscreens in borderless windowed mode. Agentstrap always enables Direct3D exclusive fullscreen, so Alt+Enter gives you true fullscreen — which can be a small performance win, because the game gets your whole screen instead of a window.

Exclusive fullscreen has trade-offs. You won't see server location notifications from Agentstrap, popout windows in the Roblox app (server browser, badges) stop working, and you may hit GPU quirks such as odd resolutions, VSync behaviour or a missing cursor. If any of that bites, fullscreen normally without Alt+Enter.

Preset bundles

A preset bundle is one click that applies a whole set of flags at once. Pick one from the dropdown and press Apply preset.

Bundle	What it sets
Default	Clears the rendering preset flags and returns them to Roblox's own defaults.
Performance	Disables display scaling, forces 1x MSAA and the lowest texture quality. Favours frame rate.
Balanced	2x MSAA and one step below the highest texture quality. A middle ground.
Quality	4x MSAA and the highest texture quality. Favours visuals.

Applying a bundle only touches the flags that bundle owns — your own custom flags are left alone. The Default bundle is the exception: it clears the five preset flags as well.

The MSAA and texture quality dropdowns update immediately after you apply a bundle, so you can see exactly what you ended up with.

Validator

Validate fast flags checks every flag name and value against the format Roblox expects, and reports anything wrong. It is read-only: it never changes or removes your flags.

Results appear in a monospace card:

All 24 fast flags are valid.

2 of 24 fast flags look invalid:
FFlagFoo = maybe (InvalidBoolValue)
DFFlagBar = 3 (InvalidNumberValue)

Only the first fifteen problems are listed; the rest are summarised as "and N more".

What counts as valid

Rule	Detail
Name prefix	Must start with `FFlag`, `DFFlag`, `SFFlag`, `FInt`, `DFInt`, `FString`, `DFString`, `FLog` or `DFLog`.
Name characters	Letters, digits and underscores only.
Place / data centre filters	If the name ends in `_PlaceFilter` or `_DataCenterFilter`, the value must be a semicolon-separated list in the format that flag type expects.
Numeric values	Names starting `FInt` or `DFInt` must have an integer value.
Boolean values	Names starting `FFlag` or `DFFlag` must have `True` or `False`.

Fast Flag Editor

At the bottom of the page is a link to the Fast Flag Editor, where you can add, edit, import and export individual flags. It's only shown when Roblox Studio is installed, because custom flags mostly matter for Studio.

Roblox's allowlist. Since September 30th 2025, Roblox only applies a whitelisted set of Fast Flags to the client. Most custom flags now have no effect on the Roblox player, even though the editor will happily accept them. Treat the editor as best-effort and don't expect every flag to do something.

Editor basics

Search filters by flag name only, case-insensitively. It does not match values.
Show preset flags reveals the flags Agentstrap manages for you. They're hidden by default.
Add new opens a dialog with two tabs: add a single flag by name and value, or import a block of JSON (pasted directly or loaded from a file).
Export JSON copies every flag to your clipboard as formatted JSON.
Delete selected removes the highlighted rows. Multi-select works.
Double-click a cell to edit it. Editing the Value is validated; editing the Name is not, and only checks for duplicates.

Importing JSON

Imports are handled carefully, because a bad config can make Roblox unstable:

More than 16 flags triggers a warning asking you to confirm.
Flags that already have a value are reported, and you choose whether to overwrite them or keep the existing values.
Invalid entries are skipped, and each one shows a message explaining why.
Entries with a null value are ignored.
Trailing commas and comments in the JSON are tolerated.

Resetting

Reset everything to defaults clears all flags. Flipping it back on restores what was there before — but only if you haven't left the page in the meantime. Navigate away, come back, or apply a preset bundle, and the undo is gone.

When changes take effect

Fast Flags are written to %LOCALAPPDATA%\Agentstrap\Modifications\ClientSettings\ClientAppSettings.json and copied into the Roblox install at launch. A running Roblox client will not pick them up, so restart Roblox after saving.

Your configuration survives Roblox updates. Because the flags live in the Modifications folder rather than inside the Roblox install, upgrading Roblox doesn't wipe them. If Roblox renames or removes a flag, it simply stops having an effect — Agentstrap doesn't migrate flags individually.

Troubleshooting

Symptom	Likely cause
My flag isn't in the editor list	Preset flags are hidden by default. Turn on Show preset flags.
The flag is set but nothing changes	Roblox's Fast Flag allowlist. Most custom flags are ignored by the player.
Editing a cell does nothing	Your UI language is translated, which breaks the editor's column matching. Use English to edit flags, or report it.
"Your Fast Flags could not be loaded"	The stored JSON was corrupt. Agentstrap backs it up and starts fresh.

Agentstrap 2.11.4 · These docs describe Agentstrap 2.11.4. Features marked new are not present in upstream Bloxstrap.