Zotero

If this is happening to you, I have an update on the situation, I have fixed it and the reason behind it is that in System Properties, (assuming a Windows computer here), go to Advanced Settings, Environment Variables, and if there is something limiting Minecraft, delete it, and RESTART YOUR COMPUTER. If this isn't your problem, sorry man, good luck.

Maybe this is also for you, but the total allocated RAM shown in F3 stays at a certain number (For me it's 455 mb) no matter what I set it to in the launcher. (E.G. 1GB, 2GB) Sorry if this all seems a bit random, but I've exerted all possible problems including console, and this is my only lead.

I also have this issue, however, I should add that in muliplayer, when you press F3, where it shows the ram you can see it rise from some 71% all the way to around 90% in either 10-15 seconds or 3-4 seconds, (depending how much you have played), cause a short (3/4 seconds) FPS spike, and return to 71%, and rise again, repeat and repeat.