Some unique attributes of CrossFilter require additional computational resources — for example, the option to capture a new Response while the Sound is playing, the low latency, the option to use different parts of the captured Response while the Sound is playing. For the most part, the CrossFilter is constrained by computational requirements, so adding more RAM would not allow you to schedule more CrossFilters than you can already play in real time.
We will add some "degenerate" cases of the CrossFilter requiring less computation to our wishlist; a CrossFilter with a precomputed, unchanging Response file and long initial latency would require less real-time computation and would allow for longer responses and more CFs in parallel (assuming you did not want to take advantage of the unique, dynamic attributes of the CF).