Against all odds, and in spite of performance issues that have lingered without official fixes since launch, Grand Theft Auto IV on PC is finally approaching its zenith point. Thanks to sweeping community efforts and a new, in-progress RTX Remix mod, the 2008 Rockstar smash hit is fast approaching a path traced visual threshold that we at Digital Foundry might genuinely recommend.

But there's a lot to pick apart about the game's historically woeful state on PC. Our analysis from resident PC gaming expert Alex Battaglia exposes GTA IV's pockmocked history as a Games For Windows title, its confusing performance scaling on modern PCs, and exactly how the new RTX Remix mod has been bolted on.

After testing the game on era-appropriate hardware, we can confirm that GTA IV never really ran at an acceptable level. For starters, its tangle of DRM systems, obnoxious enough at launch, don't even function in 2025, requiring community-built workarounds. And with visual settings set approximately near its Xbox 360 and PS3 console siblings, the game chokes on a late-'00s PC in the form of sub-30 fps refresh and frequent stutters (both from traversal and turning the game's camera). Which is all the worse when you consider that a number of visual effects from the console versions didn't actually appear in the launch PC version. (These have been restored by modders, but only as recently as this year.)

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The same game, and the same testing PC, but different performance. This is how much a jump from Windows 7 to Windows 10 can harm GTA IV performance on PC.

Weirder still is the game's inability to cleanly scale up to better hardware over the years. As a CPU-bound game with single-threaded limits, GTA IV on PC indeed nets a whopping 250 percent boost in performance when jumping to Intel Core i5-2500K CPU from 2011. But this means a jump to Windows 7 as an OS, which appears to introduce micro-inconsistencies with frame times. Worse, the same hardware running on Windows 10 has a flat 20 percent reduction in performance.

The only true solution we've seen to over 15 years of lingering performance problems is brute CPU force. A modern-day AMD Ryzen 9 9800X3D system sends frame rates skyrocketing and effectively cleans up rough frame time performance. And that's enough headroom for RTX Remix to enter the picture.

(If you're new to the world of RTX Remix, check out Battaglia's primer on Painkiller RTX from earlier this year, which includes context about RTX Remix's origins as a drop-in mod and application in other games.)

As our above video explains, project modder xoxor4d had to reverse-engineer the original GTA IV code to even get RTX Remix to work, since Nvidia's tools plug-and-play into DirectX 7's fixed-function pipeline, while GTA IV operates on DirectX 9c. This extensive effort worked to allow RTX Remix to automatically translate important elements for its ray tracing global illumination (RTGI) model, including world objects, light positions and camera information.

But xoxor4d has gone above and beyond to build a system that RTX Remix can understand and parse. As one example, the data GTA IV on PC transmits about weather, fog and post-processing is entirely opaque by default, so xoxor4d dissected the game's code to mirror its functionality in an intercept, passing on information about colour, saturation, fog density and more to Remix. This is, from our understanding, a rarity for RTX Remix mods. It fuels the mod's capacity for proper path traced handling of emissive light sources, and its constructive leaves a lot of headroom for further project growth.

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If you'd like to disable modder xoxor4d's unnatural-looking fill lights in GTA IV's RTX Remix mode, you can filter them out. Ideally, a happy medium between these two visual extremes will emerge with further community support.

And we can immediately see where the mod might go next when examining textures, which are not only still low-resolution but also lack proper material properties, along with unnatural-looking fill lights in many of the game's bespoke interior scenes. xoxor4d has left the latter in the RTX Remix mod in their current state (though they can be disabled to show a more realistic if less authentic lighting environment) while suggesting a complete overhaul in the form of custom light maps being built to replace the haphazardly and often mislabeled original fill lights.

The results are already impressive, though also apparently so dependent on an already inefficient Rockstar PC codebase, insofar as adding a translation layer and an entire BVH of drawcalls, that the RTX Remix mod somehow brings the game right back to a CPU-limited performance state. Yes, even an RTX 5090's massive headroom will be left underutilized, with 40 fps performance revealing CPU bottlenecks unless draw-distance sliders are tuned. Time sure is a full circle for GTA IV on PC.

But the community is clearly invested in taking command of GTA IV in ways that Rockstar Games has elected not to, and xoxor4d's labours will go live at Github when they're ready for community collaboration. With this in mind, better GTA IV RTX Remix visuals may not be too far in the future.