The primary thing that uses ram in NostrGram is when you scroll back in the feeds. The browser keeps all the notes loaded on the page and that requires more and more ram as you scroll back in time. Depending on the performance of your device, that will eventually slow things down as the browser has to move all the notes further down as new ones come in and you move around in the feeds. Outside of that I don't know what it might be. I can do some profiling and see if anything stands out.