How to reduce GC spikes and stutters on mobile Unity 2D during transitions

[Anthony.C]

I'm developing a 2D puzzle game for mobile using Unity, and I'm running into serious performance issues on older Android devices. The game stutters during scene transitions and complex particle effects, even though it runs smoothly on my current phone and in the editor. I've started profiling and see high spikes in garbage collection, but I'm not sure where to begin with mobile game optimization to reduce those allocations. Are there specific Unity settings or coding practices for 2D games that make the biggest difference for consistent frame rates across a wide range of hardware?