Modern producers often run heavy template libraries (e.g., orchestral templates with hundreds of instances of Kontakt or Omnisphere). One computer often struggles to process this without freezing tracks. With ReaStream, you can dedicate a secondary computer (a "satellite") solely to hosting these heavy instruments. You send MIDI from your main computer to the satellite, and the satellite streams the audio back to the main computer. This effectively doubles your processing power.
At its heart, ReaStream acts as a virtual "sender" and "receiver" for high-quality audio data.