Leverage cache

Hi,
I am a designer and not a techy type but I have installed your plugin on one of my sites which is quite large.
It is running exceptionally slow though and one of the main reasons I am getting from all performance sites is leveraging of the browser cache. I thought that is what your plugin was meant to do but clearly it isn’t doing anything??

I have it all enabled but I don’t know what else I can do – please help!

Thanks,
kat.

https://ww.wp.xz.cn/plugins/w3-total-cache/