The latest version 3.3a of uLisp for ARM now supports the PJRC Teensy 4.0 and 4.1 boards based on the NXP iMXRT1062 ARM M7 processor running at 600 MHz, and with 1 Mbytes of RAM.
These are now the fastest boards for running uLisp; see Performance.
For more details see Teensy 4.0 and 4.1.