I play Minecraft a lot and I don't think I have the worst PC.
I have a CPU named: AMD FX (tm) -6300 Six-Core Processor and a GPU named: Raden (TM) RX 460 Graphics
But I really only have 30-50 FPS in 1.12.2 and that honestly can't be.
What do you say?
The processor is just 9 years old and was not that cool back then. But also depends on the ram
Yes, still I have more in the 1.14 200-300 FPS.
The 1.12 is catastrophically optimized
I'll be told before.
Your computer has certainly seen better days.
Maybe you should think about buying / building a new one.
Even if Minecraft looks graphically not very cool at first glance, the game is very complex and has a huge game world.
The size of the game world has nothing to do with it.
Good thing I have no idea what parts you buy today.
Try to reduce the graphics settings: (install Optine as well) fewer chanks, graphics mode on fast, deactivate shader if available and close unnecessary programs in the background