Latency Comparison Numbers (~2020)
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L1 cache reference                           0.5 ns
Branch mispredict                            3   ns
L2 cache reference                           4   ns
Mutex lock/unlock                           17   ns
Main memory reference                      100   ns 
Compress 1K bytes with Zippy             2,000   ns        2 us
Send 2,000 bytes over commodity network     44   ns        0 us
SSD random read                         16,000   ns       16 us
Read 1 MB sequentially from memory       3,000   ns        3 us
Round trip within same datacenter      500,000   ns      500 us
Read 1 MB sequentially from SSD*        49,000   ns       49 us 
Disk seek                            2,000,000   ns    2,000 us    2 ms 
Read 1 MB sequentially from disk       825,000   ns      825 us    1 ms
Send packet CA->Netherlands->CA    150,000,000   ns  150,000 us  150 ms
 
Notes
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1 ns = 10^-9 seconds
1 us = 10^-6 seconds = 1,000 ns
1 ms = 10^-3 seconds = 1,000 us = 1,000,000 ns