No, no and no.
Partialy functional or non-functional Network card does not send or recieve data at all, the issue is not it it.
There is only few problem issuers.
First one could be you're downloading or have youtube active.
Second one is that you have low network flow/bandwith
Solving the problem:
First check http://www.speedtest.net before opening PandaWow, then write down the results.
Then after running pandawow launcher.exe, run speedtest again.If results match it's good for now.
As you said it starts to lag after 5 minutes, when it starts to lag run speedtest again to see if problem issuer is your internet bandwith.
Normal results:
0-100 MS/PING
Download: 1Mbps
Upload: 3Bps or 0.3 Mbps
If this didn't solve your issue just let me know
Bye.