The second value from the right is the total time consumed, so
The profiler results - using the same feed between both methods -
JSON takes 0.3996
XML takes 1.4749
And no, it's not doing these in a task because the task execution priority is way too slow at 6+ seconds to do this same thing. The task does the download, and thread 2 does the parsing. The threads don't time out if you're parsing fewer than 350 items with xml, or fewer than 500 or so items with JSON, so that is sufficient for my needs.
File sizes for the feeds are 300-400 KB. Transfer times are <1 second for either of those - basically both are insignificant to me for consideration - the profiler numbers were what I was interested in for accurate measurement. What I mean is - since the download itself is in a task node and it does its job, and then throws what it downloaded over to the parsing routine in a different thread, the transfer time and file size isn't what I was measuring.