Client_Themes is most likely the issue
i've made a very similar mod before and the exact symptoms (namely TMBI incompatibility) appeared. the way it works is the proper way to achieve custom GUI, but code that relies heavily on lots of dynamic GUI manipulation and creation will suffer from p severe performance impacts
in reality, you're probably not crashing. the game is just taking awhile to process a lot of data and if you were to wait for a bit it would sort itself out. think for yourself if the wait is worth it. i don't know the specific of how Client_Themes works, but i would imagine it's a one-time deal each play session. ie, it'll probably lag the first time you open the GUI, and then work alright from then on. this would obv change for certain mods, but that's likely what you're dealing with.