The LCDOUT is pretty fast. It really depends on the DEFINES for the LCD.

Each character takes 10-15 us to set up, then the program will wait an amount of time determined by the "DEFINE LCD_DATAUS" statement. It defaults to 50uS if no DEFINE is supplied.

Commands like Clear screen, or home cursor take longer. And are controlled by "DEFINE LCD_COMMANDUS" which defaults to 2000uS.

However, LCD data is clocked out synchronously. This means that it will not be affected by interrupts. At least not by interrupt routines that behave properly.

What kind of interrupts are you using. ON INTERRUPT, or ASM interrupts?

Can you post the code?

Darrel