Most evolutionary experts, like the late Stephen Gould, espouse Punctuated Equilibrium. Basically the theory says that environments are stable for long periods of time and then there are bursts of changes in small periods of time. The Cambrian Explosion is a good example (read Gould's book on the Cambrian, it's awesome).
If you consider technology to be like evolution, which it surely is, then infrequent advances in short periods is only natural.
For those interested in the "science/technology as evolution" perspective, have a read of Summa Technologiae, by renowned 20th-century science fiction author Stanislaw Lem. A bit dated but engrossing nonetheless; one part philosophy, one part technology, one part ... sociology? Quite interesting.
> Most evolutionary experts, like the late Stephen Gould, espouse Punctuated Equilibrium.
I agree that PE seems to fit the fossil data better than "slow, steady, gradual". But I'm not sure that "most" evolutionary experts agree. (Or maybe I'm just 20 years behind the times?)
If you consider technology to be like evolution, which it surely is, then infrequent advances in short periods is only natural.