Finder Copies:

Increase Block Size — When checked, the Finder will use larger blocks to copy files.
Use All Memory For Finder Copies — When checked, the Finder will use all (but 20k) of remaining Temporary memory as a buffer for copying and duplicating files.

Both of the above items will dramatically increase the speed for copying and duplicating files in the Finder. After checking these two items, you can expect to increase speeds by 300%. The disadvantage to these changes is that your Finder will take more of your Macs processing time (although this effect is barely noticeable on most machines). Of course, with the System 7 Pack!, now you’ll be able to choose for yourself. You can partially increase the speed by implementing only one of the patches for a compromise between speed and background operations.

I’ve checked both items on my Mac to speed up file copies. I use the Finder to copy lots of files (I backup my hard drive through the Finder) so increasing the speed of Finder copies has dramatically increased my systems performance. I’d recommend that you give these new copy routines a try. They do not affect the safety of file operations one bit. All Finder safety and verification features remain intact.

The routines work by using available memory more efficiently by doing more copying at a time, and thus using less passes.