The only way you could increase your website speed is by installing a proper cache plugin (when I say proper I mean one that doesn't ruin your website), Or If you compress each and every single image you have.
Because Images take the most space on the website.
I have a great website for you where you can compress your images that I personally used to increase website speed by up to 500% on some of my websites.
BEST COMPRESSOR WEBSITE: compress.io
Hope this answers your question.