Download speed on PS3

Hi guys, sorry if this has been mentioned before.

Just got my ps3 online again after nearly two years, via a wireless network. For some reason though, ALL downloads i run (updates, games installs, etc) are blazing through extremely fast until about 75% (sometimes a bit more), and then slow to a crawl thats so slow I thought it had frozen at first, but it does eventually complete.

I can't find any explination or info on how to fix this, hoping this sub can help.

Cheers :)