If drawings with gradients are printing slowly, you can reduce the number of gradient steps in the Printing Preferences. The fewer the steps, the faster the document will print. Conversely, more gradient printing steps will print much smoother transitions between gradient steps, but can increase printing time tremendously.
There is no benefit to increasing the number of gradient steps beyond what the printer can support. For example, most 300 dpi LaserWriters (without PhotoGrade or some other enhancement) can print a maximum of 32 gradient steps. This is the maximum gray levels that the LaserWriter can support with acceptable resolution. Selecting more than 32 gradient steps when printing to a LaserWriter will not result in better print quality of gradients, just longer printing times.