Performance: fsync vs. commit delay

Hello!

I run an [almost] OLTP system with PG as backend on Windows and on Linux.

The idea is obvious - increase performance as much as possible keeping reliability in mind and I'd highly appreciate
anyhints. 

Some questions about performance/reliability trade.

My first idea was to increase commit_delay having fsync on, since I believed commit_delay is rather conservative thing.
Readingdocs I realized it is actually not, because it prevents server from immediate writes. It means if I disable
fsynconly OS/hardware crashes are dangerous, while after setting nonzero commit_delay PG server crashes are harmful as
well.

Is my understanding correct?

What I want is to do write always but do fsync, say, every 100 ms. Is it possible to control fsyncs and writes
separately,e.g. have write for every commit and fsync as often as specified time range? 

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Best regards
Ilja Golshtein