Most vector rendering libraries have options to disable all the fancy stuff like Javascript and external links. If you manage to find one that supports it in the first place. As for resource usage, the server sends image files without decoding, so whatever forkbomb you will manage to include into your SVG will only crash Lemmy clients, so, ‘not our problem’. Maybe it will become a problem for the server when generating thumbnail image.
It really depends. One specific shop near my home has good quality frozen meat pancakes and dumplings. Yeah I have made dumplings by hand some 20 years ago, but those frozen ones are simply better. Maybe I can do some exotic dumplings with a buckwheat flour and a lot of eggs, but that would not necessarily be better, just different.
On the other hand, pasta sauce prepared from scratch will always taste better than store-bought one, mainly because the stores here only sell ketchup and mayo, and pretty much all pasta sauce here is some variety of tomato concentrate with a bit of carrots.