The RAM had nothing to do with load times. That was all about the disc drive and how the software streamed data from it and how the data on the discs were arranged. Both the GC and the Wii have a
CAV drive or Constant Angular Velocity drive. A normal CD player changes the speed of which the disc is spinning so the linear velocity is always the same. A CAV drive is always spinning at the same
angular velocity, so the Reader doesn't have to wait for the disc to spin up or down before reading, drastically improving seek times. It how ever produces uneven throughoutput as data on the outside of the streams out faster than data written on the inside of the disc.
With careful arrangement of the data on the disc with things frequently accessed placed close together and on the outside of the disc, it greatly improved load time. Even if the data was more scattered the seek times were way better than it's
CLV counterparts. All the above factors are why GC and Wii generally have much better load times.