While I was searching the internet for “performance problems running powershell against sharepoint online” I came across a link that looked like it might be useful so I thought I’d record it here:
https://soerennielsen.wordpress.com/2013/08/25/use-csom-from-powershell/
Søren Nielsen did a great job in the above article and there are some useful nuggets in the comments of his blog as well.