Well i am planning to save huge amounts of data to the disk for terrain generation and then optimize it later, but i dont know how to thread the saving of this large data, i need this to be threaded due to it will cause large frame lag spikes and that makes it almost unplayable, i dont know how to implement threading into unity without it detecting it and without it breaking anything
I use the default Unity Serialization too
If anyone can show me any examples or explain would be nice!
Well Multithreding in general is a complex task. But if you just want to dave data it should be really simple. The main thing you need to look for, is that Unity isnt thread save. Wich means you can’t call any Unity specific function outside of the main thread but you have still the holle .net/mono framework to your disposal.
There are also plenty of not Unity specific tutorials out there, just googe something like “C# threading”.
I know all of that 
but thanks, i guess ill just have to keep searching because im struggling to find a decent tutorial