Sharepoint 2010 - Networking is so high

Sharepoint system is installed in 2 computers: 1 computer install IIS, 1 computer install SQL. After a period of operation, networking of 2 computers are so high (about 0 - 50%)

I also check sqlservr.exe and afer few ms, Send Bytes up to fast :

CPU and RAM in 2 computer is so large and seem no problems:

but my sharepoint system is too slow.

How to solve it? Can anybody hep me?