I would say there is a chance that there are fewer vulnerabilities in the 60k~ lines of code contained within dillo than the in the however many million lines of code it takes to do anything with firefox or chromium.
running dillo in a bubblewrap container would probably be fine and not eat all of your available resources.
[i got my 60k loc number from running tokei in the dillo repo, doing the same in the gecko repo took multiple minutes and pegged 8 cores at 100%, might be a bug in tokei or maybe 21 million lines of code is just enormous]