Is what I have done in recent months, it did not go very well ...
The first is
Big Boobs Hard Pics | Big Boobs, Huge Boobs, Huge Tits, Busty,, the second
Big Tits Hard Pics | Big Tits, Huge Tits, Huge Boobs, Giant
The first site has photos outside, the second has the photos on my server.
In the second they are resized, optimized and reduced with jpegoptim optipng etc.
The results were extremely disappointing.
I did the same test with a couple of other sites, on other niches, I expected better results with photo optimized on server, but no.
Now, before delete the site, I would try whit photos resized, optimized etc. on a free image hosting