I want to see the performance cost of setting the style image-rendering: -webkit-optimize-contrast
for an image in a complex web page.
I know Google Developer Tools' Performance tab is powerful... but the documentation is very general, and it's difficult to distill a method to answer this specific question.
While this is primarily a question about Dev. Tools, I'll accept any answer that explains how to see the performance impact of setting this style in the context of a complex page. It would be simple enough to compare load times of two pages containing only the image and different styles, but that may not accurately answer the question of how the style impacts a production web page.
Update:
Following jburtondev's advice to load the image alone in a simple page and profile it, I found that the style costs ~200% the time in image rendering.
Using dev tools' "6x slowdown" CPU throtling, I loaded a page with just the image five times with the style and five times without. I found the "rendering" time was ~10ms with the style and ~5ms without. I'll consider that negligible, even on mobile, and assume the cost would be similar in a production page.