Extremely slow data transfer rates over LAN

[Hiatsu2k8]

I have a 10/100/1000 router connected to a 10/100 switch with a few devices attached. I found that when I transfer a single large file it uses all the bandwidth it can. However, when I try to move several thousand files it is very slow, so slow it's pointless to even try. I found on two laptops I had the same issue. On a desktop I found that it "discovered" all the files much faster but that speeds were still below 30Mbps. On the laptops the speed never exceed 5Mbps.

 

So what the hell is going on, is there anyway to fix it including upgrading my network infrastructure? 

 

Thanks as usual

 

Side question: when using all the bandwidth on the switch I notice that one device always gets all of it and one gets none. Is this because it's not a managed switch?