Usually there’s no simply answer in regards to loading speed. A lot of factors can affect it, starting from the hosting to what actually is used throughout the website.
Yes, it can be, but it entirely depends on the context. What is running from Rey and other plugins? This is essential, because Rey itself is not that large in its footprint. But assuming it can have a bug somewhere, or a poorly written code (i don’t believe there is, but i’m always improving it), plus some other plugins running next to it, than performance can drop.
I’ve built Rey with performance in mind (as much as i’ve been able to). Basically i’ve made sure that if some feature is not used, than don’t run its code.
Unfortunately i can’t give an exact answer because there isn’t but below you can find some suggestions that will clearly help.
There are lots of caching plugins out there. As a free solution, my personal favorite is WP Super Cache but there are plenty others. Just install and enable caching. It’s pretty much configured by default.
I also suggest Autoptimize plugin, which is a companion plugin to handle assets minification and concatenation. This reduces CSS and JS filesizes and also the number of requests made. Another feature of it is lazy loading images and i suggest using it. Here’s a video tutorial i suggest if you’re not sure how to handle this plugins.
A premium solution i suggest is WP Rocket. Has pretty much all features included.
Now these are personal preferences, there are lots of comparison tables out there and i’m sure there are plenty great plugins, but i just haven’t had the chance to test them.
This is a controversial topic, so that’s why i don’t want to share too much of my opinions, and instead i suggest to research on your own if your hosting is the best solution for your website. What i can say for sure is that if it’s really cheap, than cheap you get. There’s a reason why some hostings cost $4 and others $99 and more.
This one is very, very important. Make sure to optimize your images for web.
An unoptimized image can weight as much as Rey’s entire CSS or JS scripts. Be sure to optimize them!
CDNs can help your users load your website faster by serving your static resources in nodes all around the world. More in this article https://gtmetrix.com/why-use-a-cdn.html .
It’s simple, the more plugins you use, the more code runs. Make sure to enable plugins that are actually in use, they’re high quality and well rated.
In some cases, there might actually be some PHP errors that are behind the slowness. Here’s a quick and easy video tutorial to help out in debugging WordPress .