Just like I stated.
Old vs new extraction.
For me there was no difference in loading times.
I DID notice a speed boost in dml58 vs dml1.3 though.
In my case this had nothing to do with the extraction form.
Both methods were just as fast.
Tested the usual suspects;
mariokart
sunshine
windwaker
f-zero
latest dml booter
Could it be your sd card is faster? so it would make more of a difference?
Well, I tested back to back extracted vs. DiscEx compressed and did measure the difference I mentioned. With the ISO format I would not see a difference in every game, just in some and under specific circumstances. If you are casually loading games, you may not see any difference, especially if you are not very familiar with how these games played with the retail disc.
In my case, I had played F-Zero GX to death, so I was able to notice the slower loading from cup to track selection screens and verified it with the real disc. To make sure we are making the same comparison, if you are willing, please prepare an ISO and an extracted version of F-Zero GX. With each of these, go into Practice mode. This will bring you to the cup selection screen. If you haven't played through the cups yet, you'll have three available to choose from. Measure the time it takes from when you choose one until the track selection screen loads with each file system.
Another game where I would get slowdowns was Eternal Darkness, at the very beginning when the Nintendo comes up. There the audio would stutter a bit for me.