Slider Not Responsive Enough

Hi, I’m using your free version of the Master Slider. Loving the feature and UI. However, i’m having problem with the responsiveness of the slider. when i resize the window, or change from potrait to landscape at mobile phone, the slide image doesn’t resize nicely.

My site is here;
http://teklog.my/2015/09/20/pergunungan-pluto-dan-9-gambar-lain-menarik-minggu-ini/

May I know why is this happening? Is it because of free version?

I’ve tried using Soliloquoy, it seems OK on the responsiveness/resize performance, but i do not like their layout much.

Also, i’m not entirely satisfied with the performance either especially on phone, it’s a bit laggy. Do you know why?

I’m planning to use the Pro version if all is well.

https://wordpress.org/plugins/master-slider/