Mac: Displaying big pictures incredibly slow

Mac, 8.0.3494, i7 2.6Ghz MacBook Pro.

My video surveillance system sends email with photos that are quite big, 4000x3000 to be exact.

em Client takes up to 200% CPU when building the preview window, and even after finishing downloading and displaying them, when I scroll inside the preview, the fan goes on and em client eats up up to 200% CPU capacity. The scrolling, of course, is no scrolling, rather jumping. It is nearly unusable.

Wouldn’t have thought that decoding a JPEG is such a CPU intensive task in 2021, let alone scrolling a readily rendered window area. Is em Client written in perl or javascript?

Seriously, I wouldn’t know how to make this simple task that slow. Please do something about this, this slowness is a royal killjoy.