I successfully installed OS 9 Classic Mode on an eMac. At first, some of my old programs (Thinkin' Things, Millie's Math House, both edmark) ran fine, but as time went on they started jerking and freezing as they ran. I re-started and it continued to do the same thing. Any ideas on why these programs run slowly like this?
Open Activity Monitor in Applications>Utilities, select All Processes & sort on CPU%, any indications there?
How much RAM & free space do you have also, click on the Memory & Disk Usage Tabs.
Open Console in Utilities & see if there are any clues or repeating messages when this happens.
In the Memory tab, are there a lot of Pageouts?