When I apply filter or do a rotation, it so slow.

I run Win 7-64. 4gb ram. 4x cores processor.

Filters are notorious for causing Inkscape to run slower. I would suggest trying to reduce the file size as much as possible. File menu > Vacuum Defs will do that. I don't know if it will be enough to speed up the rotation, but it might. Your system stats are acceptable, and not the cause of slowness in this case...unless the file is really huge, ram might contribute to the problem. But mostly it's the filter.

There is a display mode called No filters (under Views menu), use it when having a lot of filters in the document.

Filters also get slower as you zoom in, so if you're using filters and need to zoom in close definitely use the No filters display mode.