Hey Denis,
my apologies for the delay in my reply!
I’ve tried opening the home page of your website (http://www.touhou.si/) on my machine, and the slider loads in less than a second, displaying no visible lags; I’ve also run a speed test (results), and the load time is pretty fine given the size of the page.
Could you please tell me which browser (and version, in case of IE) you are using to view the website? Also, please let me know if you are using any caching plugins on the website.
Sincerely,
Andrii / Satori Studio