Hey,
don't wanna derail GenoHacker's thread. I'm right now writing a tutorial on optimization and I have this section about exactly this topic. Do you think I should remove it?
"As a GUI user, you have the option to either use JASS or Lua as your scripting language, with JASS being the default. If you switch to Lua, not much will change for you except that upon saving your map, your map script will be transpiled to Lua, which is about 10x faster than JASS. There is the caveat that, if you choose to use external resources, you're restricted to those written in Lua. However, many creators provide both JASS and Lua versions these days or might be willing to provide a Lua translation upon request. You have to make the decision if this increase in performance is worth the downside."
WARNING: Use with caution, users have experienced mysterious desyncs, especially when using a hybrid GUI/Lua approach. There are maps that rely on Lua such as Assault The Throne, which seem to work most of the time without issues but unfortunately the lack of support from Blizzard means that any problems Lua has will probably never get fixed.