Cache

One can use variety of cache plugins. First and foremost use recommended WordPress hosting as given in https://wordpress.org/hosting/

If you think your host is good enough then check the WordPress requirements and keep your PHP version to the best possible one as per WordPress requirements: https://wordpress.org/about/requirements/

Even after that if your site is slower check for unnecessary plugins and remove them.

Still you feel your site is slow loading kindly compress your images in the page that is loading slow using tinypng.com or compressjpeg.com

If you still feel its slow try using autooptimize plugin.

If you still feel its slower then use cache plugins like litespeed cache (applies only for litespeed server), wpfastercache or w3total cache.

If you need help with paid optimization do let us know at support@sktthemes.com