Are you using that bit on the end grain to make longer boards, or on the edge to make wider boards? Personally, I'd only use that kind of a bit on end grain for making longer moldings and such. Like others have suggested, no reason to use anything for edge gluing.
The larger the bit, and the more mass, the slower the speed. There are many tables suggesting speeds for various bit diameters. I have several router bits that have tables that come on the packaging or instructions so try that first. Otherwise you can go to any web site that manufactures router bits to find the suggested speeds. Not that hard though, if your smallest router bits require the fastest speeds, and the big panel raising bits require the slowest speeds, then everything else falls in between.
In woodworking there is always more then one way to accomplish something.