From Sigmon

Basics

1. L1 cache reference 0.5 ns
2. Branch mispredict 5 ns
3. L2 cache reference 7 ns
4. Mutex lock/unlock 100 ns
5. Main memory reference 100 ns
6. Compress 1K bytes with Zippy 10,000 ns
7. Send 2K bytes over 1 Gbps network 20,000 ns
8. Read 1 MB sequentially from memory 250,000 ns
9. Round trip within same datacenter 500,000 ns
10. Disk seek 10,000,000 ns
11. Read 1 MB sequentially from network 10,000,000 ns
12. Read 1 MB sequentially from disk 30,000,000 ns
13. Send packet CA->Netherlands->CA 150,000,000 ns

From http://highscalability.com/blog/2011/9/19/big-iron-returns-with-bigmemory.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+HighScalability+%28High+Scalability%29&utm_content=Google+Reader

Storage Technology 	Latency
Registers 	1-3ns
CPU L1 Cache 	2-8ns
CPU L2 Cache 	5-12ns
Memory (RAM) 	10-60ns
High-speed network gear 	10,000-30,000ns
Solid State Disk (SSD) Drives 	70,000-120,000ns
Hard Disk Drives 	3,000,000-10,000,000ns