There are few elements to getting fast website, and I have run some tests with your website:
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Loading time is 3-4 seconds on average, which is slow, but not too slow. Some of that can will improve with the use of CDN for images, JS and CSS files, maybe 20-40% faster page loading time.
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Slow response time (initial response is well over 1 second), is due to the hosting. If you use shared hosting, you can try and switch to some better hosting (I can suggest SiteGround).
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But, you can also try to use some WordPress cache plugins. Using cache plugins adds two important elements: setup for browser cache use and caching of page content for faster loading.
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The theme is not a big part of the slow loading from what I can see.
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PHP version used is a big part of the loading speed. PHP 7 and PHP 7.1 are much faster then PHP 5.3 to 5.6, so if your hosting supports it, switch to PHP 7.
So, my advice is to start using some WordPress cache plugin (WP-Rocket is the best, but it is not free, you can use WP Super Cache plugin, it is free). Get a CDN account and set it up with the cache plugin (all cache plugins support the use of CDN). That would result in at least 50-60% better load times.
But, if that doesn’t happen, then your hosting is a problem, and then you can think of changing hosting.