In IMC things do slow down, sequencing of arrivals for instrument approaches is obviously much more complex than an airfield on its own. Building in the required separartion in the event of a MAP is a pain but not unachievable. As you quite rightly said traffic info is sometimes passed to ac that are lined up so that they can become visual and thus take up their own separation. Having combined radar positions that deal with both airfields is a big plus and dividing the tasks up to prevent overloading is also required.