if you double cpu speed, hd, ram (in some cases), vidcard, floppy, nic, soundcard, optical drive, modem....they dont all double in performance....
one aspect of it doubles, the rest stay the same
only way to "double" the system performance, would be to "double" the components speeds/performance wise
liek theotretically:
if you have ide drive 7200rpm, replace it with scsi 15000rpm drive and hd double
replace vidcard with faster/new one, performance sometimes doubles, triples, etc
ram, replace sdram with ddr ram and throughput doubles (pc133 to pc2100...not pc133 to say pc3200....then it would be more) but also the ram (if you go hihger than pc2100) needs to be utilized...like having pc3200 in a system where max dimm speed is only pc2100, wont make the ram run at 200mhz...
floppy....well i dunno hwat to do with floppy...
soundcard...i guess audio processing power would double or whatever...depending on soundcard
optical drive works....double speed, double throuput, double performance
nic..i guess going from 10mbps to 100mbps, or 1000mbps...but not actual increase....just theo for the most part
...are you talking about in practice, or theoretical?