Speed is amongst the most important issues of a website. The performance of a site is especially important when using web with mobile devices outside full speed Wi-Fi connections is getting more common. Faster websites are much more user friendly and speeding up your site is one of the easy ways to improve its search engine visibility. Begin your process by testing your site with Google's PageSpeed Insights. It will give you two scores, one for mobile and one for desktop, between 0 and 100. If it happens that your score is above 85 it means your site is performing very well and anything above 70 is pretty okay too. Unless your website is already optimised you will probably get a bad score and your site is slow. There are also other page speed testing tools, though Google's is the simplest I've found. Note that you aren't likely to get perfect score in any way, but there are certain things you can do to make your site perform better.
Even if you don't have access to these settings or don't know how to work them you can still do a couple of things to improve your website's performance. For one you can always optimise the images. Also for this there are several plugins and modules, which optimise images when you upload them to your site. Preferably optimise images before uploading them. For example Photoshop has a Save for Web & Devices option which lets you to optimise images to a point. Please note that aggressive packing can reduce the quality of an image, so be careful with it. Additionally you can create smaller file sizes with various tools. Online tools include such as Smush.it by Yahoo! which is a simple way to make your images faster. In case you are a Mac user like myself there's a free, simple and effective tool called ImageOptim for optimising images.