Something to check out on the test site - I've changed the size of images being served from the assets library to be larger.
It will now by default serve up an image that's rescaled to be max 1140px wide (which is the max width of the content in all the themes), rather than the old size which was max 430px wide.
In practice what this will mean is that images will look much nicer at the cost of being larger - but bandwidth is now much more than it was when we chose 430px as the default many years ago!
Since images auto-scale to fit into the width of a column, I don't think there should be any cases of this causing a layout problem. But please do have a look on the test site version of your site if you want to check this.
Note that this will really only affect images placed directly into content using the WYSIWYG editor. Images inserted by the CMS (e.g., in the Upcoming Events or Filtered Item List includelet) will not change (because they generally already use the higher res version).
If all seems well I'll make this change on the live site too.