Does the speed change based on what iphone or itouch generation you use?
Like for example does the speed on a Jail broken 3g differ from the speed on Jailbroken 4g.
His 3G will most likely be slowed down most by the update to 4.x software, although 4.1 does fix the speed issues a bit (but there's not a JB for it yet), and not by the JBing.