bgwriter_flush_after

I was reading about bgwriter_flush_after I found this website https://postgreshelp.com/postgresql_shared_buffers/ however, I have some questions:

First the parameter bgwriter_flush_after is amount of pages that operating system’s cache could download to disk every time Fsync is called.

Second If I want to increase the parameter bgwriter_flush_after, for instance to 2MB Will I get a better performance? and

Finally, What will be the cons of increasing this parameter?

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