What's your processor brand and speed and what type of core are you running? You can open your log file to see what core it is. Tinkers and Amber cores seem to go slowly, but Gromacs are faster. If you're not sure how to open the log you can just tell us the project number.
Do you have anything else running in the background (virus scanner, software firewall, spyware detector. . .)?
The program only needs to connect to the internet to download a project and to upload the final results. In between you can leave your computer offline.
Hardware Overview:
Machine Model: Power Macintosh G3 Series
CPU Type: PowerPC 750 (2.2)
Number Of CPUs: 1
CPU Speed: 400 MHz
L2 Cache (per CPU): 1 MB
Memory: 512 MB
Bus Speed: 100 MHz
Boot ROM Version: 1.1.1f4
Current Work Unit