The fact that Studio has issues with memory leaks (especially when using externally via API, but also during standard usage) is well-known for long time. And there were discussions about that in the forum since long time ago...
Problem is that SDL, as usually, "has that in the backlog, but it did not get enough priority yet"... :-\

In any case, 4GB RAM is actually not enough these days... it gets basically eaten all by operating system itself and there is not much left for applications.
Another thing is 'memory fragmentation'... The total amount of 'available memory' says basically nothing. The important info is 'largest chunk of available memory'... simply because applications need to allocate CONSECUTIVE memory blocks. For example, if you have 2 GB available RAM (but consisting of 5 chunks of 400 MB each), you basically won't be able to launch application requiring 500 MB RAM... (it's oversimplified, but you get the idea).
So if you do a lot of opening/closing applications/documents/etc., your memory gets fragmented soon (especially if you have only 4 GB in total) and you get into 'out of memory' problems. Reboot should help. Getting more RAM helps too.

I can concur. No end to the amount of "system out of memory exception was thrown" errors I encountered with a 4gb computer. It was crippling. Restart, close, split files, removed pictures, etc. but still had errors. Getting a new computer with 8gb of RAM has eliminated all problems. Luckily my company paid for the computer...