As part of your training, you were probably taught to us Resident loads to re-use data that has already been loaded. I have used this and taught this for several years.
However, my experience recently with larger data sets is that resident load is very slow!
A much better choice is to re-use a QVD if you have one. In fact, if you write the in memory table to a QVD (using STORE), and then use that QVD for your next load, it is still faster than using Resident!