Fundamental problem speed wise appears to mostly be an issue with the limited 65C02 arch. Quote from article "The X register has to be adjusted to make room on

Fundamental problem speed wise appears to mostly be an issue with the limited 65C02 arch. Quote from article "The X register has to be adjusted to make room on the data stack each time a function is called. It takes 7 cycles to save the X register to the hardware stack at the beginning of the function and restore it at the end. It takes 2 more cycles for DEX for each byte of local variable used to adjust the data stack pointer."