The indicator of the estimated install time is very inaccurate. The total time given after installing the first few packages is in most cases only 30 and 50% of the actual time needed. This time slowly increases during the installation. In the past, the total time decremented a bit during the install, now the total time increments a lot.
How much RAM do you have? The kernel is good about buffering the earliest packages installed, so the time is short. As the buffers fill the time is longer because files start to hit the actual disk. Little we can do about it unfortunately.
That system had 128 MB and is a PII 350. Actually, the total install time increased to 400% of the time that was indicated after the first 5-10 packages. As said, in previous releases the time slowly decreased during the install, now the deviation is much larger in the opposite direction.
At 128 MB, your computer may be going into swap later on in the install, which would degrade system performance and could cause the time estimate to vary from what it was at the beginning of the install. Like msf said, there's not much we can do about it.