I try PAUSE 1000 and does'nt seem to pause program 1 seconds. Why?

[luxornet]

For large amount of time, Pause does'nt seem to work well, the measured period is less than I expected.

main:
high Led
For i = 1 to 30
pause 100
next i
low Led
for i = 1 to 30
pause 100
next i
goto main

Above code produced about 1Hz on Led pin and not 1/6Hz!