If your ISP charges you for 5 mbits/second, but your dsl line can only carry 1 mbit/second you will have problems.
One of these problems is bufferbloat. Check for it here http://www.dslreports.com/speedtest?defocus=1
Your upload packet rate will oscillate and you will experience significant packet loss.
Dont' let this happen to you....
The UI lag will come in when FA will not send out and receive packets in time, it will stop the sim and then the sim will stop the ren, especially if ren is running at a high frame rate.