Max Nikulin <manikulin@gmail.com> writes:

> On 28/10/2021 11:04, Greg Minshall wrote:
>> 
>> i wonder if it would be reasonable to add an option such that, when
>> tangling, `org-babel-tangle` would not write a file with the
>> already-existing contents of the target file?
>> 
>> this would be helpful, e.g., for those of us who use make(1)-based work
>> flows.
>
> It was not obvious for me earlier that it should be namely an *option*, 
> not just change of behavior, since e.g. `org-babel-load-file' relies on 
> timestamp comparison of the source .org file and the derived .el file. I 
> am unsure concerning default value of such setting.

I agree that it should be the default behaviour.
The patch is attached.

On SSD, when tangling into ~200 files, the patch speeds up tangling
by almost 2x: before 7.6 sec; after 4.4 sec.

Best,
Ihor