I don’t think it’s too big, but a way you’d be able to change that is to set a maximum width to your containing div. What theme are you using? Probably a premium theme. I think you may be able to get away with adding this to the bottom of your theme’s css file:
.template-product .wrapper {
max-width: 1000px!important;
}
You can change the pixel value to whatever you want. Let me know if that doesnt work, if it doesnt I can request access to your themes and make the change for you, at the moment I just can’t tell you where exactly to put the code without looking myself.