CentOS 5 Networking :: Server Lagging After Backup (RTL8111/8168B REV 02)

I have 2 dedicated servers, one with RTL8111/8168B (rev 02) and one with RTL8111/8168B (rev 01) both running centos 5.3, the problem is like this, all things run great on the dedicated server with NIC RTL8111/8168B (rev 02) until we run backup (cpanel backup) after the backup is finish the server lags , no high load, just lags, the server is a 8 GB ram, i7 quad core, so there is no load problem or someting like this, the second server has also cpanel on it and it has no lag but it has RTL8111/8168B (rev 01) , we think that the problem is with the RTL8111/8168B (rev 02) should we update the driver ?

Here is the output from it:
2.6.18-128.1.10.el5 x86_64 x86_64
06:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168B PCI Express Gigabit Ethernet controller (rev 02) .....