I'm having some issues with PowerShell toolkit v3.2 and it being very slow running a command for the first time. System is 2008 R2, PowerShell v2.0 (same in v4.0), WFA 3.0 and PowerShell Toolkit v3.2, this is connecting to a cDOT environment running ONTAP 8.2.2P1.
I've already done the certification revokation modification and have checked all DNS settings are correct and resolution is working.
This is mirrored by every command we run, the first time it takes ~20 seconds, then every time after that 1-4 seconds regardless of how many times we run the command. If we close a re-launch PowerShell we see the same behavior again.
Just had a thought about the MTU 9000 as you mentioned that you also had this set as 9000 on the switches. Can I ask if you have the MTU set to exactly 9000 on the switches? The MTU should be higher like 9216 on the switch as the switch needs to add on header information to the packet and if the packet is sent as 9000 and the switch MTU is 9000 the the packet will get truncated.
Found out that another windows "feature" was causing this in most: auto-update of SSL root authorities and auto-update of "bad certificates". It's not only cert revocation lists that are checked by the OS by default.
Just try the resolution of VMware KB 2084025, although not directly related, this can solve a lot of issues with any kind of "SSL-connect-delay" on a box that has no or partial internet connectivity, esp. when it cannot get to download.windowsupdate.com.