No these are not the reasons: 1. This cost is minimal, and most of the time will be served from cache anyway. I'd be willing to stake a claim that literally z

No these are not the reasons: 1. This cost is minimal, and most of the time will be served from cache anyway. I'd be willing to stake a claim that literally zero people ever have worried about the cost of serving jQuery when they weren't already worried about the cost of serving a bunch of other shit that eliminating just jQuery wouldn't fix. 2. This is completely undesirable, and doesn't happen anyway because you like to a specific version which does not change from under you. The arguments in favor of hosting it on a CDN like googles are: 1) Clients who visit other sites will precache the file, so there is a chance they wont even need to load jQuery at all, and this can increase perf 2) Pushing some files to different domains can decrease load times because browsers can load files from multiple domains in parallel instead of serially like they would from one domain. 3) For smaller sites the google CDN is likely actually more dependable than your own. But if you've invested in a CDN this is no longer true.