Maybe you should check your host, if you are on a good host, your site can load in less than one second which is great in my opinion.
In the opposite, if you are on a bad host, with a old PHP version, most themes will feel bloated to you.
I have tested this on Flywheel and WP Engine. Even with caching on a site, there’s going to be times where the site must load for non-cached users, and even with caching, the 15 CSS files that are exported and multiple JS files leave these sites sluggish, definitely not in less than 1 second. Even with a managed WordPress server with a server response time of .26 seconds we’re looking at 24.6 seconds “Time to Interactive.”
Even the oceanwp.org site takes 12.6 seconds for time to interactive: https://developers.google.com/speed/pagespeed/insights/?url=https://oceanwp.org/
The google tool are recommendations, if you want to test the speed of a site, go on a site like pingdom, then you will see that the main site loads in less than 1s30 and the demos less than 1s.
Here the main site: https://tools.pingdom.com/#5a25946605800000
And here a demo with WooCommerce: https://tools.pingdom.com/#5a259554cbc00000
563ms, I think it is pretty good, right?
Before putting 1 star on a theme, try the speed with the right tools.
About the CSS and JS files, you can easily group them in one files with a plugin like WP Rocket or even free plugins.
Thanks.