Ray Tracing and FPS: The Performance Cost of Realistic Lighting

Ray tracing has been called the biggest leap in game graphics since the move to programmable shaders. It produces reflections, shadows, and lighting that look dramatically more realistic than traditional rendering techniques. But realism comes at a steep cost: ray tracing can cut your frame rate in half, or worse. This guide explains what ray tracing actually does, why it is so demanding, and how modern tools like DLSS and FSR help you get the visuals without sacrificing playability.

What Ray Tracing Actually Does

Traditional game rendering, called rasterization, approximates lighting using clever shortcuts. Shadows are precomputed or rendered as simple textures. Reflections are usually screen-space, meaning they only show what is already visible on screen. Global illumination is faked with light probes and ambient terms.

Ray tracing takes a fundamentally different approach. Instead of approximating where light goes, it simulates individual rays of light as they bounce around a scene. For each pixel, the renderer shoots rays into the 3D world, traces their path as they hit surfaces, and calculates the color based on the materials and light sources they encounter.

The result is lighting that behaves physically. Mirrors reflect objects that are off-screen. Glass refracts what is behind it. Soft shadows fade naturally at their edges. Light bounces into corners and fills them with subtle color from nearby surfaces.

All of this looks beautiful. It also requires enormous computational effort.

Why Ray Tracing Is So Expensive

Rasterizing a frame requires computing one color per pixel, with lighting approximations that are cheap to evaluate. Ray tracing a frame requires, for each pixel, tracing one or more rays through the scene, finding their nearest intersections with geometry, and then often spawning secondary rays to handle reflections, refractions, and shadows.

The work scales with the number of rays per pixel, the complexity of the scene geometry, and the number of bounces simulated. Even with dedicated hardware acceleration — the RT cores in NVIDIA's RTX cards, the Ray Accelerators in AMD's RDNA 2/3/4 cards, and the matrix engines in Intel Arc — ray tracing adds substantial per-frame GPU time.

The performance impact varies by effect:

• Ray-traced reflections are expensive because every reflective surface spawns additional rays.
• Ray-traced shadows are moderately expensive, especially for soft shadows from area lights.
• Ray-traced global illumination is very expensive because light must be traced as it bounces between surfaces, often over many frames (which is why some games use denoising and temporal accumulation).
• Path tracing — the most complete form, used in fully ray-traced remasters like Cyberpunk 2077 with RT Overdrive — is the most expensive of all, tracing many bounces per pixel and producing dramatic FPS reductions.

A game running at 120 FPS without ray tracing might drop to 50 or 60 FPS with full path tracing enabled, even on a high-end GPU.

The Hybrid Approach Most Games Use

Very few games ray trace everything. Most use a hybrid approach, rasterizing most of the frame and applying ray tracing only to specific effects where the visual benefit justifies the cost.

A common pattern is:

1. Rasterize the main scene with traditional techniques
2. Ray trace reflections only on surfaces marked as reflective
3. Ray trace shadows only for the key directional light
4. Optionally apply ray-traced global illumination to improve ambient lighting

This hybrid approach lets games offer a "Ray Tracing" setting that improves visuals without making the game unplayable. The fully path-traced modes are usually optional and aimed at owners of the most powerful GPUs.

How Upscaling Recovers Performance

Because ray tracing is so demanding, the industry developed a complementary set of technologies to recover the lost frame rate: AI-based and spatial upscalers.

The idea is simple: instead of rendering every pixel at the final resolution, render the frame at a lower resolution and then use sophisticated algorithms to reconstruct a high-resolution image.

NVIDIA DLSS uses AI models trained on supercomputers to upscale lower-resolution frames. The latest versions (DLSS 3 and 4) also generate intermediate frames using AI, which can dramatically increase effective FPS in GPU-bound scenarios.

AMD FSR uses spatial and temporal algorithms to achieve similar upscaling. It runs on a wider range of hardware, including older GPUs and competitor's cards.

Intel XeSS is Intel's AI-based upscaler, similar in concept to DLSS.

Native upscalers in engines, such as Unreal Engine's TSR, are built into the game engine and do not require vendor-specific hardware.

The combination of ray tracing plus upscaling has become the standard high-end gaming configuration. Enable ray tracing for the visuals, enable DLSS or FSR to recover the frame rate, and you get the best of both worlds — usually at a small cost in image sharpness that most players do not notice in motion.

The Setting Tiers Most Games Offer

If you are tuning a game that supports ray tracing, you will typically see settings arranged in tiers of cost:

• Off — full frame rate, traditional rendering only
• Ray-traced reflections or shadows only — small FPS cost, noticeable visual improvement in specific scenes
• Ray-traced global illumination — larger FPS cost, more pervasive visual improvement
• Full ray tracing / path tracing — largest FPS cost, most dramatic visual change, often requires upscaling to be playable

For most players on mid-range hardware, the second or third tier offers the best balance. The top tier is best reserved for high-end GPUs or for showcasing screenshots.

How to Decide Whether to Enable Ray Tracing

Use this framework:

1. Establish your target frame rate. For single-player games, 60 FPS is usually the minimum. For competitive games, 120+ FPS.
2. Test your baseline FPS with ray tracing off. Run an FPS test and play the game with an overlay to confirm your starting point.
3. Enable ray tracing at a low tier and measure the FPS impact.
4. Enable upscaling to recover frame rate, and judge whether the image quality is still acceptable.
5. Move up or down the tiers until you find the combination that hits your target frame rate with visuals you enjoy.

The Future of Ray Tracing

Ray tracing hardware is improving rapidly. Each generation of GPUs includes more RT compute units and better denoising hardware, which reduces the per-frame cost of tracing rays. Software is also improving: denoisers are getting better, reconstruction techniques are reducing the number of rays needed, and game engines are learning to use ray tracing more efficiently.

Over time, the performance gap between rasterized and ray-traced rendering will narrow. But for now, ray tracing remains a meaningful performance cost that players need to manage consciously.

Final Thoughts

Ray tracing is a genuine visual leap, not a marketing gimmick. It produces lighting and reflections that simply cannot be matched by traditional techniques. But it is expensive, and ignoring the FPS cost leads to a beautiful game that stutters and feels worse to play.

The answer is not to avoid ray tracing or to enable it blindly. It is to understand the trade-off, use upscaling to recover performance, and tune each game to find the balance that works for your hardware and preferences.

Start by testing your baseline FPS, then experiment with ray tracing settings and upscaling to find the configuration that delivers both the visuals and the smoothness you want.