I'm not sure if this is a bug or normal behaviour of ST3.
I am using ST3 for a java project. Although this java project has several large directories (>1GB), the actual source code is 0.5MB total. It's almost as though ST3 is caching my files through threads so they open faster.
My computer only has 4GB of ram and ST3 is using 2393.9 MB of it. Please see my screenshot below
It gets so bad that my system locks up on occasion.