He would still need more information about your computer. Do you use wireless? It is possible he could have entered your network if you have no passcode or encryption set up. As for the weird Asian address, there are proxy programs one could download to mask their IP, and one of them my friend's father uses allows you to use international IP masking, which would make the most sense. Another thing is to check "netstat" for any incoming/outgoing connections by going to: Start>Run Type in "Cmd" then type netstat and it should provide you a list of all incoming and outgoing connections. Run it while you are not using Internet Explorer or messengers to get a better look. If you aren't running a wireless router/modem gateway, then this seems highly unlikely.
For your processor speed, you can sort by CPU usage in task manager, or find a freeware program that monitors your processor usage in real-time and see what program(s) are using the most resources and investigate them. You may considering upgrading your security software.. I don't know what you are using but I recommend ESET Smart Security if you can afford to pay for it. Run a full system scan in Safe Mode (Not with Networking) and see if your anti-virus picks up anything. Get Malwarebytes and scan that in Safe Mode too. The final step to any security package to to do a full scan with HijackThis! and post your log on here, or on any forum that supports reading HijackThis logs and get an expert to look at it and their opinion on files that are running in your memory.
Hacking probably isn't near as dead as I consider it to be, but there is a lot more these days hackers have to consider before doing it and if this guy is only home now and then, from a psychological standpoint I doubt he's after your files, etc. The way internet connections work, if you're on cable for example we all connect through one node and then it's split out to houses. That doesn't explain processor speed really, but it would explain slower internet times/download times. Maybe this person is doing some heavy internet work i.e downloading programs, music, videos, etc. And that can create some congestion in your speeds too; especially if he is tapping into your network wirelessly.
A final thought, use WPA encryption or WPA2 if your router supports it for your wirless signal. WEP can be cracked using Linux for the most part, though once again it depends on the knowledge of your neighbor. Setting up a WPA2 passcode with 20+ characters; letters, numbers, and symbols.. almost guarantees you not to let your wireless be shared with anyone.
Let us know,
Tim
