The biggest driver is the size of your library. There are quite a few threads on the Roon forum discussing track count vs. computing power requirements. 512 MB of RAM is going to get fairly tight very quickly, however, especially if you're hoping to perform EQ or other DSP operations. DSP may pose a challenge for the processor as well.
(For what it's worth, Roon's user interface is faster now than it was a year ago - a rarity among software applications, in my experience.)
