How to raise the lpub processing speed?

[jass]

I use the latest version of lpub and found some model is very slow in the step creation, more than 10mins for adjust 1 modification.
Question 1.
I don't know if there is something wrong in my ldr or mpd file as some models by more parts has no problem.
Question 2.
If I want to update the hardware for my PC, what's the most importantk? Memory?

Thanks for your suggestion.