Why minecraft Lags

i have noticed that most people are confused why minecraft lags so much well i'm pretty sure i have came up with some of the answer:
guys/gals just imaging how many blocks this game has to load up seriously like on normal render distance it probably has to load up over 100,000 blocks probably way over that. which other games has to load up that many things.i will give you and example call of duty maps they all don't need massively long coding they just need to be there and be recognized as a wall they don't need code to say they can be mined and how long do they fall what blocks are around them what is there id is

now for the mobs and stuff well they do pretty much nothing to my computer i spawn about over 500 then i start having noticeable lag so they ain't much of a problem

now onto mods they may have to load up mods so yeah considering that it is not a main piece of code it is harder to make use of that's why you will notice that TNT from different mods MAY have more lag or less really depends on the modder if they make simple but efficient code

plus the game engine i doubt is that good i'm not sure what it is but yeah if i forgot anything please message me and tell or put it in the comments