Only marginally, he's got a repeating textual effect, as apposed to a gradient.

A gradient would be what, about 1px by 150px atleast, granted his is something by 800px height.

But it shouldn't make too much of a difference and a gradient might look more out of place.

It may require an extra 80kb, in this day and age thats nothing as most people are on faster than 56kb.

However this extra file size does need to be taken into consideration for bandwith consuption, while 40kb may not be alot, after 10,000* hits thats now 40mb.

*Most browsers, after one page will cache the background rather than reloading it, however if it can't cache, or the cache is removed (periodically most often) then it will reload.

Just make sure you grant enough bandwith to cater for graphic intense sites.