cFosSpeed is a specialized network driver designed to optimize your internet connection by reordering data packets through a method known as traffic shaping. Unlike standard Windows drivers that process data on a first-come, first-served basis, this software analyzes network traffic in real-time to prioritize time-sensitive data like online games and VoIP calls over bulk transfers. By managing the queue of outgoing packets, it ensures that heavy downloads or uploads do not choke your bandwidth, allowing for responsive browsing and low latency even when the line is under full load.
Key Features
- Traffic Shaping Technology: Automatically reorders internet data packets to ensure urgent traffic is transferred first, significantly reducing lag during simultaneous uploads and downloads.
- Layer-7 Protocol Analysis: Inspects data packets to identify the specific application generating them, allowing for precise prioritization of games, streaming media, and voice calls over P2P or file transfers.
- RWIN Expansion: Dynamically adjusts the TCP Receive Window size to optimize current download speeds, often overriding the default, static Windows settings for better throughput.
- Wi-Fi Access Point Optimization: Reduces latency for smartphones and tablets connected to your PC's hotspot by prioritizing their traffic effectively within the local network.
- Real-Time Status Monitor: Displays a customizable overlay on your desktop that visualizes current bandwidth usage, ping times, and active connections, helping you spot network hogs instantly.
Use Cases
This software is essential for online gamers who need consistently low ping times to avoid rubber-banding, even when roommates or family members are streaming 4K video on the same connection. It also benefits remote workers using VoIP applications like Zoom or Teams, ensuring clear audio and video quality during video conferences by preventing background file backups from saturating the upload channel.
cFosSpeed stands out by installing itself as a kernel-level driver rather than a simple application, offering deep packet inspection and control that standard bandwidth limiters cannot match.
Version 13.10 Build 3004 — June 2025
- Implemented a major rewrite of the core networking code to significantly enhance throughput and efficiency.
- Added support for modern Task Offloading technologies, including Checksum Offloading (IP, TCP/UDP), Large Segment Offloading (LSO), and Receive Segment Coalescing (RSC).
- Improved Traffic Shaping logic to utilize multiple simultaneous Internet routes, benefiting load-balancing configurations like combined LAN and mobile adapters.
- Optimized pass-through LAN traffic handling to ensure maximum speed for data that does not require shaping.
- Introduced a new, high-performance API for retrieving connection statistics, offering up to 20x faster response times.
- Added a Connection per Second (CPS) history graph to the current connections dialog, covering the last 15 seconds.
- Enhanced full-screen application detection, now supporting configurations where the full-screen window is on a different monitor than the status window.
- Fixed compatibility issues with ad hoc VPNs by ensuring out-of-band packet information remains intact during processing.
- Reduced CPU usage significantly, maintaining barely noticeable load even during 10 GBit/s data transfers.
- Included new UDPv6 pingers to further stabilize connection monitoring and latency reduction.
- Added Windows 10 toast notification support for update alerts (Build 17763 and newer).
