While doing some tests, I noticed an constant increase in memory usage on a command that simply asigned variables and created string pictures:

Maybe the issue was caused by the repeated usage of Show string pictures, reseting the same pictures over and over again.

I suspect the same issue can happen on the original rpg_rt and patches.
To mitigate that, I suggest Avoid doing all the steps from commands like "Show Picture", "Show String Picture" and "Move Picture",
If the result turns to be the exact same as it was before.

In case of move picture, maybe the command should just wait until the amount of frames it's marked to use.