"Lead is heavy stuff so, obviously, the new lead-free instructions are going to be much lighter and, therefore, much faster!"

No, no, no.

"Lead Free" is the latest *package* - nothing to do with roofing material [Note - the marketing people didn't like "Pin Free" - they thought it sounded too muck like M&S shirt packaging]. Many common problems have been solved by the lead free, zero pin count package:

** Immune to static damage
** Immune to soldering damage
** Immune to power supply noise
** No reset controller required
** Unaffected by poor board layout
** Easy replacement after failure

One of the main thrusts behind this development, however, was customer feedback. Basically people were getting fed up with the ever decreasing pin pitch and increasing pin count on modern devices. The engineering population as a whole is ageing - eyes deteriorating, hands shaking - how are we supposed to desolder a VQPF4096 in the garden shed, I ask you?

Speed gains are provided by the shorter signal paths - with a conventional package each instruction has to come out along the pins, through your circuit then back in along the pins. By getting rid of the pins this bottleneck has been eliminated allowing these devices to run ReallyQuick (TM).