An idea that might be even easier for you...

'setup code...
counter var word

main:
counter = counter + 1
portb.7 = counter.0 'portb.7 toggles at the rate of the LSB
portb.6 = counter.12 'portb.6 toggles at the rate of the LSB/4096
pauseus xxxx 'add your pause to get the rate down
goto main

The loop will always execute at the same speed.