The difference between 3205, 3199, 3187 and 3312 is really not a lot when you think that this is measured in microseconds.

The command you are timing is this:

LCDOUT $FE,$80,"TMR1 = ", dec temp

The time this takes will depend on the value of temp. As temp increases, it takes longer to convert it into a decimal number (dec temp), and as the decimal number increases in number of digits, it takes slightly longer to write it to the screen.

What happens if you reset the timer value each time? Try adding TMR1H=0 and TMR1L=0 just before each time you start the timer.