plypencil Why make something yourself when there is LUA? Also: Scripts will make the particle-logic even slower. Best way to get more flexibility is to turn TPT into a framework with a core-plugin. So people can simply download plugins that add elements and such to TPT.
plypencil LUA is 'kind of save'. If you want to create a script-language, you have to think about a lot more then how the syntax looks. Think about interpreter speed and error handling, etc.
the performance hit should be minimal, i know of powdergames with interpreted scripting that reach ~600fps. the problem is the way tpt is structured atm makes this very hard to do, maybe in the distant future.