Most posters restrict themselves to sensibly-sized images.

A minority are either unaware of the negative impact of posting large images

• (i.e. it slows down page loading - quite significantly in the case of mobile devices;
•  and it can corrupt the pagination of forum pages)

or are insufficiently technically savvy to resize their images.

How about imposing a hard limit on posted image size (600 x 600 pixels, say)?

TinyMCE could be tweaked to automatically either reduce the size of larger images - or reject them.

then how are we to post these images to derail stupid troll's threads ?