Thread:LOTRMod/@comment-26767096-20170228190157/@comment-25101089-20170302152218

There is no hard limit on how big the map could be, but it's determined by what I would consider a reasonable amount of RAM to expect most people to have available. At the moment, I think 2GB is a fair expectation, and that's enough to run the mod on high settings with shaders installed and still have plenty left over.

I'm not sure exactly how much RAM the map uses, but I remember checking it once in a profiler thing and seeing a total of around 200MB. That comes from loading the image itself for rendering, and also from storing the array of biome IDs (which is at least 4x less memory than the image itself). This is all due only to the image size - 3200x4000 - and not to the image complexity or the number of colours or anything like that.

So theoretically, if the map size was doubled, if that 200MB figure is correct it might increase to around 800MB. And that would then be pushing the total 2GB limit for some people. I'm not sure - I haven't tested it thoroughly - but if you want to, just resize your map.png in the mod and  see how your RAM usage changes.

Other features like adding new blocks, items, mobs, biomes, and so on have so little RAM usage that there's no point even considering them. For example, registering a new block in itself barely affects the memory usage. A block is just an object with a few properties defined, which will require perhaps a few dozen bytes of memory at most, and using that block in the world causes no increased memory usage because it's just a different ID within the set of 4096 possible IDs for the game to reference.

What does increase memory usage is having a larger number of block or item textures to stitch together into a texture atlas, because at some point the texture stitcher will run out of space to include all the textures and have to increase the size. And I have noticed that the mod now needs a 2048x2048 texture atlas for blocks and a 1024x1024 for items, compared to the 1024x512 atlas used in vanilla 1.11 for both! But this is with thousands of block textures, and after 4 years of working on the mod, so it won't increase any time soon, and that is still less than the map uses. In conclusion, adding new blocks and items is nothing to fret about.

And on a relevant note: Allocating more RAM does not improve your performance unless you are already running out of RAM!