you can use procmon in order to find out which dll gets loaded, from where and when.
Run procmon, define a filter for npp and then start npp.
It needs a bit of training but if you are really interested in finding out what does what
check out the sysinternals tools as well as everything Mark Russinovich has posted/blogged.
Once you are at the level to understand how process, threads, libraries, drivers … work together
download hxd and start investigating memory.
Other useful tools can be found at nirsoft.