Cfeturn timeout on query

I am having a really strange issue where an ajax call to a cfc is hanging up on a very specific query return(99% of time it works). Query runs fast, strip out some html base 64 images tags(reReplaceNoCase), then return query. If I don’t strip out the image tags the query returns fine, I can log out a JSON serialize of both queries, prior to return and they pass JSON parsing.

Any idea how to bug shoot a hung up cfreturn?