Performance and testflight in an iphone app

Do analytics services like testflight live slow down performance --is there any problem including those in an app store build?

I'm wondering if in the process of contacting a server they will cause glitches jerks or changes in frame rate if they are talking to a server behind the scenes. When using www to talk to the server isn't there usually some sort of yield, that pauses the update loop? Couldn't that affect animation for graphic intensive games?