I vaguely recall there being a long loading time issue that occurred if you had custom soundtracks turned on but had removed a playlist or folder that GT5 was set to use. Have you messed with that at all?
To ping the PS3, go to the Settings tab of the XMB > Settings and Connection Status List, and get your IP Address. Then from a computer on your same home network, open a command box (windows key + R to open the run box and type 'cmd' without the quotes and hit enter), then at the prompt type 'ping ip_address -t' without the quotes and where ip_address is the IP Address you got for the PS3. let it run for a good 20-30 minutes or even an hour if you can, watching it periodically for lost requests. After the time has transpired, hit control-c and it will stop and give you an overall report. Packet loss should always be 0 or you have a bad connection for some reason. Ideal latency is also under 10ms average for any device on your LAN, otherwise it could be your router overloaded by bittorrents or the like. You could also try pinging Google the same way to see if your outbound connection or modem has any of the same issues 'ping www.google.com -t' (without the quotes). Outbound latency you want under 100ms average to be ideal.
To ping the PS3, go to the Settings tab of the XMB > Settings and Connection Status List, and get your IP Address. Then from a computer on your same home network, open a command box (windows key + R to open the run box and type 'cmd' without the quotes and hit enter), then at the prompt type 'ping ip_address -t' without the quotes and where ip_address is the IP Address you got for the PS3. let it run for a good 20-30 minutes or even an hour if you can, watching it periodically for lost requests. After the time has transpired, hit control-c and it will stop and give you an overall report. Packet loss should always be 0 or you have a bad connection for some reason. Ideal latency is also under 10ms average for any device on your LAN, otherwise it could be your router overloaded by bittorrents or the like. You could also try pinging Google the same way to see if your outbound connection or modem has any of the same issues 'ping www.google.com -t' (without the quotes). Outbound latency you want under 100ms average to be ideal.