Nvidia's latest GeForce Game Ready Driver, version 591.44 WHQL, has arrived as a crucial update that addresses significant performance issues introduced by a recent Windows 11 update while restoring legacy PhysX support. This certified release incorporates what was originally a rushed hotfix into a stable, WHQL-certified package, demonstrating Nvidia's rapid response to system-level compatibility problems affecting gamers and content creators alike. The driver specifically targets performance regressions that emerged after Microsoft's KB5066835 update for Windows 11 23H2 and 22H2, which had been causing measurable frame rate drops and stuttering in various games and applications.

The Windows 11 KB5066835 Performance Regression

Microsoft's KB5066835 update, released in late February 2024 as part of Windows 11's monthly security update cycle, introduced unexpected performance issues for Nvidia GPU users. According to official Nvidia release notes and corroborated by multiple tech publications, the Windows update caused measurable performance degradation in games and applications. The problem appeared to stem from compatibility issues between the Windows update and Nvidia's display driver model, resulting in reduced frame rates, increased stuttering, and overall diminished gaming performance on systems that had previously been running smoothly.

Search results from March 2024 indicate that the issue affected a wide range of Nvidia GPU users, with reports spanning from entry-level GTX cards to high-end RTX 4090 systems. The performance regression wasn't limited to specific games but appeared as a system-wide issue affecting GPU performance metrics. TechPowerUp's testing showed measurable performance drops of 5-15% in various benchmarks following the Windows update installation, with some users reporting even more severe impacts in specific titles.

Nvidia's Rapid Response with Hotfix Integration

Nvidia's response to the Windows 11 performance regression was notably swift. The company initially released an emergency hotfix driver (version 551.46) within days of widespread user reports, then quickly incorporated those fixes into the official 591.44 WHQL release. This two-stage approach allowed affected users to obtain immediate relief while Nvidia worked on full WHQL certification for the complete driver package.

The 591.44 driver represents a significant milestone as it's the first WHQL-certified release to include the KB5066835 compatibility fixes. WHQL (Windows Hardware Quality Labs) certification indicates that Microsoft has tested and approved the driver for stability and compatibility with Windows operating systems, providing users with greater confidence in system stability compared to beta or hotfix drivers.

Restoration of 32-bit PhysX Support

Beyond addressing the Windows 11 performance issues, driver version 591.44 marks the return of 32-bit PhysX support, which had been absent from recent Nvidia driver releases. PhysX, Nvidia's proprietary physics engine, has been a staple in gaming for years, providing realistic physics simulations in supported titles. While 64-bit PhysX support has been maintained, the absence of 32-bit support had affected compatibility with older games and applications that still rely on the 32-bit architecture.

The restoration of 32-bit PhysX support is particularly significant for gamers who enjoy older titles or use applications that haven't been updated to 64-bit architectures. This move by Nvidia demonstrates continued support for legacy gaming experiences while maintaining forward compatibility with modern systems. According to Nvidia's documentation, the 591.44 driver includes complete PhysX system software version 9.24.1031, ensuring comprehensive physics simulation capabilities across both architecture types.

Technical Improvements and Game Ready Features

The 591.44 WHQL driver isn't just about fixing problems—it also delivers performance optimizations and new features. As a Game Ready driver, it provides day-one optimization for \