Hey See22,
the loading behavior of the slider is not determined by the theme itself but rather by the plugin which has been included with the theme (for free, I must note :) – the Slider Revolution, which is the most popular slider plugin on Envato Marketplaces. There are several measures I would recommend trying before switching to another slider:
First and foremost, I would advise reducing the size of all images in the slider, by down-scaling and/or reducing dimensions. Currently the images in the slider are over 1 Mb each (some even larger than 3 Mb, which makes the entire page load quite slowly (please see the detailed speed test here). It is highly recommended that any image in the slider does not exceed 300-400 Kb (the less, the better) – this will ensure quick loading of the entire page for all users.
Furthermore, I would recommend trying the “Lazy Load” option in the slider settings – please go to the “Revolution Slider” admin section, click on the “Slider Settings” for the slider you need to edit, and activate the “Lazy Load” option in the “General Settings” box (do not forget to save the changes). This will speed up the loading even further.
Thirdly, in case the above measures still leave space for improvement, or for some reason cannot be implemented, I can propose a more drastic solution – adding a preloading animation to the website, for example this one. I can recommend it because I’m using this code myself in my latest Shogun theme. A preloader will display its own screen until the website is fully loaded, avoiding any of the loading issues which may arise.
Finally, in case you still decide to go for another slider, please let me know which one, I will help you set it up and integrate it into the theme.
Sincerely,
Andrii / Satori Studio