I used Game Maker from around v4 up to v7, and, unless it's gotten significant performance boosts since then, I can guarantee you that you will get
far better performance with LOVE than you do with Game Maker. I would go so far as to say that the performance will often be anywhere from 10 to 100x better (depending, of course, on what you're doing).
One thing to keep in mind: Game Maker is object-oriented. LOVE uses Lua, so it does not have many object oriented programming (OOP) features setup at start. Now setting up OOP (either prototype-based or class-based) features in Lua is fairly painless (though some parts are harder than others...but those parts probably won't be required for most simpler games), but the point is that it's not setup to start with. In Lua, you typically setup objects using tables. A table in Lua is an associative array, but it is also has many qualities that an "object" typically has. Read here if you're interested:
http://www.lua.org/pil/2.5.html &
http://www.lua.org/pil/16.html (the entire "Programming in Lua" book, of which the first edition is free online, is a great place to learn Lua btw:
http://www.lua.org/pil/contents.html ).
Oh, and to expand on something that josefnpat mentioned, one great thing about LOVE and the LOVE community is all the free libraries and code snippets available.
Almost every feature I've missed or problem I've had has already been implemented by a library or solved by a code snippet on the forum.
Here is the wiki's list of libraries:
https://www.love2d.org/wiki/Category:Libraries
I definitely recommend going through the tutorials (especially the video tutorials). They're all easy to follow, and they really give you a great idea of whether you like LOVE and Lua:
https://www.love2d.org/wiki/Category:Tutorials