Flash Drive as Ram issue?

Firstly a big thanks to the people who maintain portable apps. They must be the programs I use most.

I recently changed from Open Office to Libre Office, and am having a problem.
When I am using Libre Office from my flash drive (4gb) it decides to use the flash drive as RAM. This means that moving an image 3 pixels to the right takes 15 seconds or so, due the write speed of the flash drive.
I know that it is using the flash drive due to watching the access light go crazy when if hangs.
This isn't a problem with small files, but as soon as I open my 9.3 mb research document even just typing becomes an issue. (Only a sentence or two before it hangs for a second)

Does anyone know what is causing this, and possibly a workaround?