When i look at the results from whoisactive I cant really see any queries that look that intensive as regards burning cpu. I can however see a lot of logins from the account that we use for replication with numbers in the cpu field ranging from13,000 to 24,000 but then next to that is says status 'sleeping' for this login name.

Is there a way to tell if replication was the culprit for the high cpu usage ?

I take it the numbers spwhoisactive returns in the cpu column are the time measurement measured in milli seconds ?