Thanks for your reply robtillaart.
I understand that interrupts do not miss pulses. However, it is my understanding that if you're in the middle of outputting a command on the serial communication pin, then you detect an interrupt, the output command gets halted mid sentence so to speak so the interrupt routine can run run which causes the command being written to the LCD to be messed up resulting in the LCD displaying garbage. Feel free to correct me if any of my assumptions are incorrect.