The issue is wireless.. remember there is really very limited bandwidth and trying to copy a few files that might add up to 1GB is not fast over wireless..
Also for reasons best known to Apple, they decided QoS was not necessary.. so there is no ability by the system to detect important packets and bulk data packets.
It seems as though we should be given more customized settings in terms of how Time Machine goes about its business now that Lion uses versions. I mean, things get automatically backed up anyway, so wouldn't it be time to allow us to set Time Machine to back up every 1, 4, 6 or 12 hours instead of the default of just every hour or nothing at all?
Apple believe in the mind over matter approach.. we don't mind. you don't matter. We dictate what is going to happen .. you like it!! If you don't.. tough.
There is a utility for setting time intervals for TM backup. Just google .. I don't have a link.. I did try it and found it less than reliable. And that was SL.
A solution is to change your network around.. use a different router and connect the TC to your computer by ethernet. Speed over ethernet is hugely better than wireless.
For laptop that is inconvenient..
Another suggestion is to use wireless on 5ghz.. that still means the TC has to be located basically in the same room where you work.
Apple deliberately restrict the speed of 2.4ghz to 130mbps.. whereas the new TC and new MBP or Air can link at 450mbps on 5ghz.. of course that is only link speed.. transfer speed is many times less.
You need to setup the TC properly.
Give short names to wireless and different name for 5ghz so you can force the link.
Set fixed channels. At 5ghz try high channel and low channel and see which works better for you.
I've tried the utility too, but didn't like it. I might just use my Time Capsule as my wireless router, but not backup to it. Perhaps I'll connect a firewire drive to my laptop and use that as my time machine backup. I'm not crazy about the ethernet option because that would mean switching around my set up. Currently, my TC doesn't sit anywhere close enough to be able to connect to my laptop via ethernet, and even if I could, I didn't buy a wireless router and hard drive only to connect with wires.
I much prefer backup systems like Carbon Copy Cloner where you can set the interval and customize your backup to work they way you need it to. For instance, I would have it back up twice a day - once in the middle of the night, and once in the middle of the day - at times when I wasn't using the machine. This would cover me based on what I use the computer for and not get in the way.
Thanks for your insights and input.