What does "files" options actually do?

[anotheruser584]

I have spent like an hour on a dummy project and still could not get an idea of files options.
Form docs: --files Load files, include and exclude from tsconfig.json on startup.
Sorry for stupid question, but I haven't found a solid info on how ts-node is working...
Does ts-node do in-memory compilation of TypeScript files? Or is ts-node using some "temp" folder in node_modules? Depending on the mechanism of how ts-node is working the explanation above ( Load files, include and exclude from tsconfig.json on startup) my have different meaning... "Load files..." load where? What is the real-world use case of this options?
Also docs says that TypeScript Node does not use files, include or exclude, by default..
The include and exclude are TypeScript options and it is pretty clear to me. But how are these options affection the files options?
So by toggling files options I can "load" or "don't load" these files... But still I don't see any difference with this option on/off.
Please help me to figure out the purpose of this option

[cspotcode]

The docs for "--files" aren't great. Like all things open-source, given limited time I've had to prioritize other things. We would accept a pull request that improves the documentation.

In the meantime, this explanation I posted elsewhere should help at least a little. #1185 (comment)

In short: ts-node --files behaves like tsc; ts-node without --files does a performance optimization.

To see the differences, try tsc --showConfig, ts-node --files --showConfig, and ts-node --showConfig. In the output for all 3, take a close look at the "files", "include", and "exclude" arrays.

Again, we will accept a PR improving documentation because I agree that it should be improved.

[anotheruser584]

Thanks for the reply and sorry for the late response - I've got sick.
Looking into config shed some light indeed.
If you don't mind I would like to clarify this statement:

ts-node without --files does a performance optimization.

While testing locally the files flag I didn't spot any performance difference. But let's say I'm running e2e tests in NodeJS on something like Azure DevOps or Jenkins or whatever.
I'm running 700+ tests (that are 400+ files) in parallel in Chrome which means the process is already pretty expensive resource vise.
The resource of the virtual machine is limited compared to the local setup because... well, because of money.
Does it mean it would a good idea to turn the files flag off while running code in the cloud? And if "yes" are there any cons I should be aware of when turning the files option off?
p.s. I have found this article that bumped up performance drastically https://medium.com/aspecto/ts-node-ram-consumption-12c257e09e13 so I would like to know what else am I missing.

[cspotcode]

Check out our performance recommendations here: https://typestrong.org/ts-node/docs/performance