Half the time I try to go to a website using the standard browser on my curve 8530, the page won't load, or if it does it takes forever. This just started to happen about 2 weeks ago. It started happening after I forgot to top up my Virgin Mobile prepaid account for it, they then cut my service for a few hours until I was able to top up, and pay for my month. I tried re-sending the service books, and re-registering the host routing table, but that doesn't work. This happens on both wifi, and cellular. Also, everytime I try to install or upgrade anything from app world, it's almost impossible, because of how slow it is. It literally takes almost an hour to install a 3MB app.
Maybe it is time to check the available memory on the smartphone. If there is plenty of memory, then perhaps take a back-up of the device contents and perform a security wipe and reinstall the applications and the backed up data using a selective restore.