A blog or website's speed is very important, because most web surfers will not waste their time on slow loading websites. If it is very slow, they will automatically close it and will never return. They won't subscribe, they won't even like your site. Speed is really important and you should optimize your site for the visitor to have a great time surfing your blog/ website.
The lower speed time the better and there are tools that could help calculating its loading time:
These sites are self explanatory, all you have to do is put the necessary details.
Increase your loading Speed
If your blog still takes a lot of time loading, try changing its template but do not forget to back them up.