Use Metal, not the default renderer
Press Esc in Roblox, go to Settings, and check Rendering under Graphics Mode. Set it to Metal if it is not already selected. Metal is Apple's own graphics API and is built for Apple hardware — it generally performs better than the fallback path Roblox uses when Metal is unavailable or not selected.
Lower Graphics Quality
Set Graphics Mode to Manual so quality does not shift mid-game, and start around Quality 5. If you are still below 60 FPS, step down to 3, then 1. This is the single biggest lever on any Mac without a discrete GPU.
Check Activity Monitor before playing
Activity Monitor is the Mac equivalent of Windows Task Manager. Open it with Cmd+Space, type Activity Monitor, and press Enter. Click the CPU column to sort by usage, and quit anything unexpected that is using significant CPU. Browsers with many open tabs are the most common offender.
Use High Power Mode
Some MacBooks (Apple Silicon models with active cooling) have an Energy Mode setting under System Settings > Battery. Selecting High Power keeps the chip running at full speed instead of favoring battery life — the closest thing macOS has to Windows' High Performance power plan. Not every Mac model has this option; if you do not see it, your Mac does not support it.
If Roblox stutters above 60 FPS
Mac users have reported choppiness specifically at frame rates above 60, tracked as an engine-level issue on Roblox's own developer forum rather than something a setting fixes. If this matches what you are seeing, capping your in-game frame rate at or near 60 is a reasonable workaround until Roblox addresses it directly.