Game Lag White Paper › L2 Client OS and device

Other apps on the same device using up bandwidth Other apps saturating the link

Cause ID co-other-apps · Primary owner External (External) · Also Game team (Client development)

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When cloud sync, a large download, or a game patch runs on the same PC, game packets have to wait in a queue.

Why Another app maxes out the upload or download → Effect Game packets pile up in the queues on the PC and the router → On screen Ping shoots up, input lag, fast-forward

Symptoms

Input lag, Fast-forward

Factors

Latency, Jitter

Who’s affected

Just me, Same household

When

Randomly

Owner

Primary owner External (External) · Also Game team (Client development)

Game team action items

Make our own launcher and patcher pause or throttle background downloads during play.

External action items

Tell players to cap download speeds and turn off automatic updates while playing.

On the graph

Rises with load · RTT, PC traffic sent and received

Where to look

Record Network Interface\Bytes Sent/sec and Bytes Received/sec in Performance Monitor together with ping. Same approach as a bufferbloat test, where you deliberately start a large transfer with ping running

Confirmed if

Ping rises by tens to hundreds of ms while downloads or uploads run close to the connection speed, and drops back as soon as the transfer stops

Ruled out if

Ping rises while PC traffic is low: “Bufferbloat (router queue)” from another device in the same household, or the ISP segment

Check with

The player’s own environment

Sources

1. Introduction Bufferbloat.net
   When network equipment such as a router buffers too much data, latency spikes sharply (bufferbloat)
2. Delivery Optimization reference Microsoft
   Windows Update downloads (Delivery Optimization) adjust dynamically to available bandwidth by default, and caps can be set on background and foreground download bandwidth
3. Network-Related Performance Counters Microsoft
   Network Interface: Bytes Received/sec and Bytes Sent/sec counters
4. Tests for Bufferbloat Bufferbloat.net
   If ping rises while a speed test saturates the connection with ping running, it’s bufferbloat

See also

Same layer: L2 Client OS and device

• Background processes taking up CPU
• Power saving and thermal throttling
• Timer resolution
• Mobile app sent to the background
• Wi-Fi ↔ LTE/5G switching
• Packet inspection by security software
• Receive buffer overflow
• Client low on memory and swapping
• Out of graphics memory (VRAM)
• Wi-Fi background scanning
• NIC power saving and driver issues
• Throttling when the window is minimized or unfocused
• Overlay software interference
• Display, input device, and frame generation latency

Same symptom (Input lag), other layers

• Rendering load from large crowds L1 Client game process
• Packet processing bottleneck on the main thread L1 Client game process
• V-Sync and the render queue L1 Client game process
• Congested Wi-Fi channel L3 Home network
• Bufferbloat (router queue) L3 Home network
• RRC state transition delay (mobile radio power saving) L3 Home network
• Propagation delay (physical distance) L4 Internet path
• Satellite internet (LEO/GEO) L4 Internet path

View the interactive card with figures and simulations