Large IP Block = Lots of ARP traffic

The company I work for owns a /18 - all of which exists at one location and is routed by a single router. There is no subnetting or VLAN in place, so each host is seeing a TON of ARP traffic. Also the router is struggling during peak usage times and I think that if I could cut down the amount of ARP it had to do I could stretch the life of the router. A big problem is that many of the 200+ machines have IPs on them that span many possible subnets, so it would be difficult to use VLANs to solve this problem. And would VLANs even really solve this problem? Wouldnt the router still have to do a ton of ARPing, only not every host would see every ARP? Can someone explain to me how this works? Wouldnt every VLAN still see every ARP because they go out to

Basically here is the current network design: internet - cisco router - cisco L3 switch - - hosts I suppose internet - cisco router cisco L3 switch host would not be out of the question for us to implement, but can someone explain to me how a setup like this would work and reduce overall ARPs?

Any ideas, requests for more info, etc... would be great.

Thanks!