I don't think he was trying to make you lag, instead I believe he was proving a point that it's annoying to scroll past your bulky signature that slows load time, especially in threads that you post a lot in. All for some image that you don't have a personal relationship with.

Also, not everyone has a $5,000 computer, for those of us browsing on netbooks with small screens and slower processors or older pcs, your signature can really slow things down/take up space.