Hi Lagewegict,
There are several things which you can try for this situation.
First of all go into the system BIOS and set the system profile to max performance.
The intel igb cards have a power saving feature which sometimes cause delay in connections.
Other then that please update the igb driver to the latest version:
https://my.vmware.com/web/vmware/details?downloadGroup=DT-ESXi5X-INTEL-igb-4017&productId=285
After the driver has been updated we unload the mod in vmware and reload it with certain parameters:
vmkload_mod - u igb (Unloading the module)
vmkload_mod igb InterruptThrottleRate=8000,8000 (Reloading the module - Dual port NIC)
vmkload_mod igb InterruptThrottleRate=8000,8000,8000,8000 (Reloading the module - Quad port NIC)
Hope this helps,
Cheers