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The Computer Latency Calendar


I recently saw this Gist and Interactive Page, so I thought it would be cool to update it for the 2020s. This can serve as a visualization of how fast a modern computer is.

How to read this calendar

Imagine 1 CPU cycle took 1 second. Compared to that, A modern 4.0 GHz CPU has a CPU cycle of 0.25 ns approx. That's 4,000,000,000 times difference. Now, imagine how that CPU would feel one second in real life.

ActionPhysical TimeCPU Time
1 CPU Cycle0.25ns1 second
L1 cache reference1ns4 seconds
Branch mispredict3ns12 seconds
L2 cache reference4ns16 seconds
Mutex lock17ns68 seconds
Send 2KB44ns2.93 minutes
Main memory reference100ns6.67 minutes
Compress 1KB2μs2.22 hours
Read 1MB from memory3μs3.33 hours
SSD random read16μs17.78 hours
Read 1MB from SSD49μs2.27 days
Round trip in the same data center500μs23.15 days
Read 1MB from the disk825μs38.20 days
Disk seek2ms92.60 days
Packet roundtrip from California to Seoul200ms25.35 years
OS virtualization reboot5s633 years
SCSI command timeout30s3,802 years
Hardware virtualization reboot40s5,070 years
Physical system reboot5m38,026 years