The Australian international joined the club last week until the end of the campaign and put in an impressive debut, but he could not prevent his new employers from slipping to a 14-19 defeat at the hands of Northampton Saints at the Madejski Stadium on Sunday.
"The speed of the game was very surprising," O'Connor told reporters. "I thought Super Rugby was fast but I was really blowing out there, that's for sure.
"It felt great. The club and all the boys have been awesome since I arrived and I am really looking forward to my time here.
"I didn't feel 100% and can get better. I wanted to perform. It was one of the best pitches I have played on. It was just a shame we could not get the win."
London Irish travel to face Newcastle Falcons in the LV Cup on Sunday.