Size of Largest Problem Instance
Solvable in 1 Hour

Time Complexity functionWith present computerWith computer 100 times fasterWith computer 1000 times faster
nN1100 N11000 N1
n2 N210 N231.6 N2
n3 N34.64 N310 N3
n5 N42.5 N43.98 N4
2n N5 N5 +6.64N5 + 9.97
3n N6 N6 +4.19 N6 + 6.29

Figure 1.3 Effect of improved technology on several polynomial and exponential time algorithms.

So, a thousand-fold increase in computing speed with the 2n algorithm only adds 10 to the size of the largest problem instance we can solve in an hour, whereas with the n5 algorithm this size almost quadruples.

From Computers and Intractability: A Guide to the Theory of NP-Completeness , Garey and Johnson, W. H. Freeman Press, 1979, ISBN 0-7167-1044-5