Filters are pretty processor intensive so can cause lag especially with mousemove. You may be able to make it appear less laggy by reducing the setTimeout in your JS.
It is set at 300 so try 100 instead.
circle.style.opacity = '0';
I have an old version that I just updated to use blur and seems smoother although its not exactly the same effect,
Yes the demos are only for one element you would need to loop through all the relevant elements and apply the js to each in turn. It looks as though that would be quite hard for the mask method you are using but would likely be simpler in my demo to implement. However I haven’t looked in detail at that. There is also the problem of what carousel you are using and how to implement code into that nicely.
It would be much easier if you just did a whole image unblur instead of the mouse cursor method. the reverse of this effect basically.