google insights and plugin

We’ll post the same response given elsewhere:

You are right, Google has recently changed their page speed tool to suggest aggressive image optimisations.

Although of course it is possible to compress images more aggressively than what TinyPNG and TinyJPG do, the quality tends to suffer. Our image optimisation is intended to automatically determine an optimal balance between quality and size.

We do plan to look at our JPEG compression algorithms this year, to see if we can tune the optimisation to return smaller images in cases where it doesn’t harm the output quality.

Hope this helps understand the results given by Google.