Digital Foundry Direct Weekly DF Direct Weekly #229: Xbox Ally X Hands-On, Sweeney Defends UE5, id Software Doom TDA Deep Dive!
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Sep 1, 2025 Get ready for a hands-on dive into the Xbox Ally and Ally X, with insights on their ergonomic design and quirks. The hosts dissect Tim Sweeney's controversial comments on UE5 performance issues, revealing a deeper look at developer challenges. Exciting graphics breakthroughs from SIGGRAPH are discussed, along with the innovative Shader Glass that revives nostalgic CRT visuals. Plus, they explore the competitive landscape of AMD and NVIDIA GPUs, and brainstorm fun ideas for future content!
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UE5 Defaults Can Create Performance Pitfalls
- Alex highlights core UE5 engine issues (traversal stutter, shader permutation handling) that can cause stalls even with proper developer practice.
- Epic has been addressing these with multi-threading, Fast Geometry and shader compile improvements across 5.4–5.6, but legacy pain remains for early adopters.
Ray Tracing Scales Better For Many Lights
- SIGGRAPH work shows ray-traced direct lighting (ReSTIR) can scale better with many shadow-casting lights than raster shadow passes.
- Epic's 'Mega Lights' proves usable RT lighting on PS5 at a flat per-pixel cost, but usually at 30 FPS and with future API/geometry improvements needed.
RTGI Solved Doom's Dev Bottleneck
- id Software moved Doom The Dark Ages to ray-traced GI to avoid massive build sizes and unbearable iteration times of precomputed pipelines.
- Ray-traced workflows drastically shorten iteration, storage and build-time costs for large, dynamic maps compared to offline baking.