@pparent
thanks for the explanation, it's indeed faster than the more convoluted process I was following. So I did about 6 messages each having 5 photos, lomiri-messaging memory footprint increased steadily by about 100 K for each message (that I never actually sent, it was a dummy number). When I closed lomiri-messaging all this memory was reclaimed by the system, and if I open it again I don't get back the high memory use even if I open the same contact.
So there may be a leak but it hardly seems a blocker on my phone - that is, my current use of the phone is that as soon as I have finished using an app, I close it, and each evening I shutdown the phone for the night. You may use your device very differently of course.