Epic Games CEO Tim Sweeney says Unreal Engine 5’s performance problems aren’t about the engine — they’re about when developers choose to optimize

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As a researcher exploring the dynamics of game development, it’s clear that the Unreal Engine has gained significant popularity, standing as one of the preferred platforms for constructing contemporary games. Notably, an increasing number of studios are transitioning to Unreal Engine 5 (UE5), such as Halo Studios, who have decided to bid farewell to their long-serving Blam! Engine.

Following numerous adjustments over the years with the Slipspace Engine, which is essentially an advanced take on Blam!, the team is now transitioning completely to UE5 (Unreal Engine 5). The intention behind this shift is to alleviate difficulties and enable contractors to devote their entire work hours towards development rather than learning a fresh engine.

However, the journey isn’t entirely seamless. While UE5 is acclaimed for its breathtaking graphics, it’s also known for encountering performance issues in numerous games developed using it. Recently, Epic Games CEO Tim Sweeney has shared his insights on why these performance struggles are prevalent in games built with this engine.

A reputation for performance woes

The groundbreaking UE5 was unveiled in 2020 through the Lumen in the Land of Nanite tech demo on PlayStation 5. This demonstration highlighted two significant advancements: Lumen, a technology for creating dynamic lighting and reflections, and Nanite, a system that enables developers to incorporate high-quality movie assets into real-time work.

Initially, the display was breathtakingly beautiful and sparked great anticipation. But as UE5 games began to appear, numerous gamers found themselves facing an entirely different reality. A wave of complaints about lagging, crashes, low frame rates, and heavy system requirements soon ensued.

Titles like Lords of the Fallen, Wuchang: Fallen Feathers, and Xbox’s own Oblivion Remastered faced criticism due to performance issues when played on various platforms such as PC, Xbox Series X, and Series S.

It’s worth noting that not all Unreal Engine 5 (UE5) releases have faced issues. Games like Senua’s Saga: Hellblade II and Fortnite demonstrate the engine’s capabilities when optimized effectively, showcasing UE5’s ability to deliver impressive graphics alongside stable performance.

Epic Games CEO Tim Sweeney responds

Tim Sweeney clarified the concerns pointed out by addressing them head-on through a post called “This is Game,” which was later relayed by Clawsomegamer. In essence, he shared that many game developers initially construct games with high-performance hardware in mind, and optimizing for lower-spec machines often gets pushed back to the final stages of production.

In an optimal scenario, studios should prioritize optimization over high-end hardware development from the start, rather than focusing on top-tier hardware initially and then working on optimization and low-spec testing at a later stage. This way, optimization can be addressed before the complete content is built out.

According to Sweeney, Epic is working on solutions to make that process easier.

We are focusing on two main areas: enhancing engine performance by introducing more automation for optimization across various devices, and promoting education among developers to ensure they adopt ‘optimize early’ as a standard practice. If additional assistance is required, our engineers are readily available.

It seems that lately, optimization has taken a back seat, as technologies such as DLSS and FSR have been employed more frequently. These techniques, involving resolution scaling and frame generation, are often utilized to conceal performance problems rather than addressing them directly.

Today’s games are significantly more complex compared to a decade ago, making it challenging for developers to solely address the complexity at the engine level. Thus, collaboration between game creators and engine makers is crucial. Additionally, we’re leveraging our Fortnite optimization insights to enhance the performance of Unreal Engine, ensuring that titles run smoothly even on computers with less powerful hardware specifications.

Tim Sweeney, Epic Games CEO

Sweeney emphasized that merely fixing the issue with the engine isn’t sufficient anymore. Today’s games are more intricate than before, requiring developers to collaborate with the engine, rather than fight against it.

From my perspective, Tim Sweeney isn’t so much defending Unreal Engine as he is critiquing the work methods of developers and advocating for a shift in development culture and optimization approaches.

The developer perspective on UE5 struggles

Essentially, developers like Eric Rajot, when discussing Beautiful Light, claim that subpar performance is more often due to incorrect practices rather than issues with the engine. This perspective mirrors Sweeney’s stance that optimization should be given more focus during the early stages of development.

It’s not universally accepted among developers that everyone shares the same viewpoint. Specifically, Ian Maclure from Bossa and Lee Devonald at Rocksteady have highlighted the Xbox Series S as a potential bottleneck, particularly due to its memory limitations being a significant hurdle. However, Digital Foundry has offered a somewhat contrasting opinion, acknowledging that several UE5 games can adapt impressively on the Series S, but this often requires additional development time, a luxury not all studios can afford.

In other locations, Daniel Vávra from Warhorse Studios has publicly criticized Unreal Engine 5 (UE5). While Kingdom Come: Deliverance 2 garnered acclaim for its RPG elements, visuals, and storyline, the team opted for CryEngine over UE5. Vávra asserted that UE5 is not yet ideal for large-scale open-world projects, going as far as suggesting that CD Projekt Red’s Witcher 4 development team admitted the engine was still not prepared to handle full-scale open-world streaming effectively.

As a devoted enthusiast, I’m thrilled to share that by June 2025, the Unreal Engine will have evolved yet again with the arrival of version 5.6! This update promises to deliver some exciting enhancements such as refined shader compilation, an even swifter Lumen, and improved Nanite foliage, making it a remarkable leap forward for us creators.

Indeed, Sweeney’s perspective seems valid; it might be advantageous for developers to focus on optimizing games for lower-end hardware initially during development. This approach could potentially enhance experiences on consoles such as the Series S and the upcoming Nintendo Switch 2, which have less performance flexibility.

For the Nintendo Switch 2, being the fastest-selling console launch ever, it could be beneficial for game developers to aim at less powerful hardware. This strategy would allow their games to be released on a larger number of consoles.

The issue at hand won’t miraculously vanish with a snap of fingers, and some hurdles related to UE5 might persist indefinitely. However, it’s heartening to observe Sweeney acknowledging the challenge, and Epic demonstrating their readiness to aid studios experiencing difficulties.

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2025-08-27 15:10