IIS or Abyss for Windows Server ?

[Eurylink]

What are consideration about Web Server to use with 3CX v.9 ? I installed v.9 with abyss on Windows 2008 R2 machine. Abyss seems to be slower loading than cassini. This is caused by OS (in this case windows server) ?
I'll test for some days then I'll restore 3CX on IIS platform (previous v.8 was with IIS).
I imagine IIS is the first choice for Microsoft Server OS .... or not ?

Thanks

 

[clarityscg]

We have been using Abyss in lieu of IIS sind the roll out of Ver 9 Beta 1 and have experienced no slow down or other issue as comparred to IIS. We are running on vmWare slice - Windows Server 2008 R2 with 5Gb of Ram allocated.