While you have BD running check task manager, and keep an eye on it.
I"m curious the specs on the laptop.... I'd assume processor or memory issues(is there much else?). If your connection is fine.... if it was after a longer period of time 1 hr 2hr I'd be more likely inclined to point to a memory leak or just low memory in general. If you have vista and an internal card reader, also assuming you have an usb stick or SD memory card? If so you can use readyboost and the USB stick as additional memory, if it helps you may want to buy another stick of RAM for your laptop.
Now if it is a processor bottleneck.... run only BD when possible and your sol pretty much
I tried to keep things relatively simple, and of course my favorite suggestion...... Attempt using different browsers, or try using one browser for BD and another for your other web browsing, I use chrome for BD IE for surfing.