I also noticed some slow downs. Just to give an example: after the last update my phone was suddenly really fast. But that only lasted for two days. After that period I am restarting my n900 everyday to get some speed out of it. The slow downs can get very annoing: imagine that I cannot surf on the internet and update my email at the same time. This is only after 48 hours uptime. Another thing is that my desktop shows slow downs; when I press something, it doesn't immediatly respond.