Secrets of Olympus - sluggish game play magically corrected itself

I demo'd Secrets of Olympus on in 2008 and liked it but used up all my demo time. When it went on sale, I downloaded 2 versions from different sites to test it before buying. One game was super sluggish; the other was a little sluggish. Took my chances and bought it. After downloading, it played worse than either of the games from the other sites. Did all the updates that tech support usually requests and tried again. Same thing. Contacted support and they issued a game credit. Thought I would try it again and tonight it worked perfectly; just a little sluggish after hours of play. Has anyone else had a problem like this that magically corrects itself?