How is the hosting architecture? To me it seems that it is served by plain Apache, which is flexible but very slow. If this is the case it could easily be improved, for example by putting an HTTP cache in front. I would suggest Varnish, which could already improve delivery by a factor many (it should be able to saturate outgoing bandwidth). And if this is not sufficient other improvements to hosting architecture could be possible, avoiding to spend the man hours to migrate pages. I’d be happy to discuss further ideas and help where I can.
Regards,
Willem