For example...
I was syncing my 3g while playing a video in itunes and with firefox just idle in the background.
The video was lagging and when firefox was used, web graphics were slow to come up.
Another glitchy thing that happens while syncing my phone is Safari will crash when changing the homepage in preferences.

Thank you!

ps...My specs:
Model: MacBookPro5,5
Processor Name: Intel Core 2 Duo
Processor Speed: 2.26 GHz
Number Of Processors: 1
Total Number Of Cores: 2
L2 Cache: 3 MB
Memory: 2 GB
Bus Speed: 1.07 GHz