Also, the loading/saving time is not only dependent on the image size, but also on the format. JPEG is a relatively complex format with various stages of transforms and compressions, which also takes time to decode/encode. Furthermore, the JPEG file size depends on the "quality" (the quantisation factor), so a general statement like "JPEGs are smaller than PNGs" is useless, especially considering the loss of information in one but not the other. As eXpl0it3r says, JPEG is a good format for photographs, while PNG is better for graphics or images that need to be pixel-perfect.
If i broke it up into more and smaller textures and sprites would that make a difference?
Yes, there would be more textures
Difference with respect to what? If you really care about performance, measure it. The graphics card and driver as well as other factors may also have an influence. But in general, don't make your life complicated if you don't need to. There is also a hardware-dependent limit to the texture size.
By the way, the class
thor::BigTexture I wrote automates the splitting into smaller textures for you and is used very similarly to
sf::Texture.