FL Studio Portable still uses ASIO drivers. If you plug your USB drive into a computer with an audio interface, you can install the interface's ASIO driver (temporarily) and achieve sub-10ms latency. The portable nature does not hinder this.
continues to be one of the world’s most beloved DAWs (Digital Audio Workstations), known for its pattern-based workflow, powerful piano roll, and lifetime free updates. The portable version takes that flexibility a step further — letting you run FL Studio directly from a USB drive, external SSD, or cloud folder without a traditional installation. fl studio 21 portable