I see nobody is reacting to your problem.
I have (almost) the same problem, but with 10.7.5.
Not only Time Machine freezes up (over WiFi and USB-connected), but also my Music downloads (everything else works fine) to my iPhone 5 (with iTunes 11.1) and also Spotlight (indexing for minutes and then freezes).
All these 3 actions (which usually take longer than anything else) freeze up after 3 to 15 minutes. Never the same, always different durations. Very annoying.
On the other hand: ever since I disabled Spotlight, my MacBook Pro A1286 is as fast as when I bought it in 2009.
This all happened suddenly, out of the blue. No added software, hardware. No changes in prefs.
I had my hardware checked. I have done a memtest. All the tricks in the book. To no avail.
Aopple techs tell me to wait till Maverick......some solution ;-)