Here's something i never noticed before, but while working on my current high resolution project there appears to be a huge vacuum of ram. I've been working on a simple 1-layer 56-frame animation at 1920x1080. The only thing about this particular project that is different from my previous ones is the size of the frame. I'm not adding any more frames, nor am i increasing the complexity of the drawings by any significant amount, yet ram usage by pencil2d has increased to over 3gb in the course of a few hours. This happens both in the morevna 0.5.4 debian package and recent source from git.

Sorry i have no more specific information.

EDIT: RAM use jumped by about 2gb immediately after selecting and moving the contents of a layer, so maybe that helps a little. Last night that same action resulted in my desktop becoming essentially unresponsive (some very minimal but ineffective cursor response, and sporadic short bursts of audio from the music that was playing) for half an hour before i decided to just press the power button.

Debian Testing (jessie) 64bit
Intel i5 / 6gb ram / Intel HD 4000 graphics