What Is Bufferbloat? The Hidden Cause of Internet Lag
You might have fast download speeds but still experience lag. The culprit? Bufferbloat — a common but poorly understood network problem that causes your latency to spike whenever your connection is under load.
What Is Bufferbloat?
Bufferbloat occurs when your router or modem has excessively large network buffers. When these buffers fill up during heavy usage (like downloading a large file), packets get queued instead of transmitted quickly. This queuing adds latency — sometimes hundreds of milliseconds.
How Does It Affect You?
Gaming: You're playing fine, then someone in your house starts streaming Netflix. Suddenly your ping jumps from 20ms to 200ms and you're rubber-banding everywhere.
Video calls: Your Zoom call is crystal clear until a cloud backup starts running. Now you're freezing and stuttering.
Web browsing: Pages load slowly when downloads are running in the background, even though you have plenty of bandwidth.
How to Test for Bufferbloat
Pong.com's speed test includes a built-in bufferbloat test. We measure your ping when idle, then measure it again while your connection is under load. The difference tells you how much bufferbloat you have:
Grade A (0-5ms increase) — No bufferbloat. Your router handles congestion perfectly.
Grade B (5-30ms) — Minimal. You probably won't notice any issues.
Grade C (30-60ms) — Moderate. You may experience lag during heavy usage.
Grade D (60-200ms) — Significant. Real-time applications will suffer when others use the network.
Grade F (200ms+) — Severe. Your connection becomes nearly unusable for real-time tasks under load.
How to Fix Bufferbloat
1. Enable SQM (Smart Queue Management) on your router — this is the most effective fix
2. Look for routers that support fq_codel or CAKE queue discipline
3. If your router supports QoS, enable it and prioritize latency-sensitive traffic
4. Consider upgrading to a router with better buffer management
5. Reduce the number of simultaneous heavy transfers
6. Some ISPs offer modem/router combos with better queue management — ask yours
The Bottom Line
Bufferbloat is one of the most common causes of intermittent lag. A fast connection with bad bufferbloat is worse than a slower connection without it. Test your connection at pong.com to find out if bufferbloat is affecting you.