dev-ui-performance

Canvas rebuilds are reduced by partitioning dynamic elements onto their own Canvas or child Canvas. Any element updating more than once per second, such as health bars or timers, must be isolated so static elements are not rebuilt every frame.

Draw calls are reduced by packing all UI sprites into Sprite Atlases grouped by usage context, such as Atlas_HUD or Atlas_MainMenu. Never mix atlas sprites with single-texture sprites on the same Canvas, since crossing texture boundaries breaks batching.

Use RectMask2D for rectangular crops like scroll viewports because it avoids stencil buffer writes and is GPU-cheaper. Reserve Mask with an Image only for non-rectangular or circular clipping where the stencil cost is justified.

ScrollRect lag happens when all list items are instantiated at once instead of being pooled. Use an object pooling pattern that reuses pre-allocated cells and binds data without instantiating, which is mandatory for lists exceeding 10 items.

Yes, every Image and Text with raycastTarget enabled is iterated during touch events, including decorative elements. Disable raycastTarget on backgrounds, decorative icons, read-only labels, and progress bar fills, keeping it only on Buttons, Toggles, Sliders, and InputFields.

Avoid string allocations by using the TMP SetText overload with format parameters, such as SetText("Score: {0}", score), instead of interpolated strings. Also disable word wrapping on fixed-length HUD text to skip reflow calculations.