Issues with Garageband and MacBook Air

I have an Early 2015 Macbook Air. I had very few complaints until I started using GarageBand and encountered System Overload errors. I only have 3 folders on my desktop. My hard drive is just over half full. Clean My Mac OSX tells me all is wonderful - and it is until I try to use Garageband. I have 4G of RAM and only about 25 MB available. I've freed up as much RAM as I know how - are their programs that are known RAM hogs?

If I get a Mac Mini and use the laptop as a monitor, will I get the benefit of the extra RAM? The only processor intensive thing I do is sound creation/design/editing. If I must get a new laptop, which one do y'all recommend for what I do? I use the laptop a lot, but mainly for reading articles, writing an email, playing the occasional game, shopping, etc.. (aside from the music production - which Im getting back into after 15 years.) Also, is ProTools still any good

Thanks for reading.

Warmly,

Brad