What is the rate of compression and the time for a republish node?

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I am using a republish node in a launcher file to republish an image as a compressed image. It is working well.

My questions are two;

1. What is the rate of compression of the republish nodes? (meaning how compressed they are)
2. What is the time it takes to do the compression (on the fly)?

I suppose that these rates can be changed and that larger compression takes more time. Can these rates be changed?