use png if you want crisper images, because jpeg compresses them, and if you can, try to keep the dimensions in powers of 8, as processors prefer it, and 100 kb shoulden't be too large as to harm performance (if only you could feel the cringe I got when testing out the 3D game engine I built when rendering 3,000,000 polys....), computers now can take a ton of stress
, and depending on how sfml orders the storage, images might be rounded up to the next largest size i.e 64, 512, 1024, have luck