I'm running KStars, Ekos and Indi on an Odroid XU4 with 2GB RAM and 64GB eMMC with Ubuntu 16.04.
KStars and Ekos handling is very smooth but when I (accidently) zoom more than 100% into an image the memory usage increases very fast and the system starts swapping which slows down the whole system and I have to wait some minutes before I can abort the action. It's happening in Fitsviewer but also in the focuser window.
I assume Fitsviwer resizes the whole image so it takes much more space in memory. Maybe there is a way to calculate the region of interest where I zoomed in and resize this part of the image. Of course, this needs more CPU because moving the region of interest needs to recalculate the resized image region but it can save memory.
I don't that possible without a LOT of work since you can zoom to 400% and then drag the image around. Imagine what is required to keep doing ROI all the time. Maybe I can add "Limited Memory" option which would turn off all things that are memory intensive (like debayer..etc) along with locking zoom to 100% max
EDIT: I added "Limited Memory Mode" to advanced options in KStars. This only applied to FITSViewer. Will improve memory stuff with time. For now it limited zoom to 100% and turns off auto-debayer and auto-3D cube.