With tethering (whether 4g HotSpot or Root Tether), I had lots of issues. Overall the speed was great, but the response times were poor and some pages would never load.
My Fix: (Thanks to Linux making adjustments easy), was changing the MTU setting on the computer to MTU=1300. This improved things so much that i never usually wait more than a second for any page to respond and usually instantaneous overall.
For Linux, just go to the network settings and change MTU (GUI, Ubuntu at least)
For Windows, they don't make it easy, but this link does:
Hope this helps your problems out. If not, I would try booting into Ubuntu Live CD and see if you can't get better speeds. (remembering to try changing the MTU.) Using a Linux LiveCD to determine a Windows problem or if a hardware problem is one of the easiest methods I have found to start out with.
I pay for the HotSpot Service and overall, I find using the root tether (Garden Tether) to be much snappier and less battery drain. So, if you happen to have your phone rooted, then I would try the Tether App found on the market. Since your paying for the 4g HotSpot, it won't matter which program you are using as the data is calculated the same (IE:the 4g HotSpot data usage tallies on the phone as if it were phone data. You might notice that one the verizonwireless website that the hotspot tab doesn't who any usage because of that.