[Pasy]

I’m not sure why, but I find it quite annoying when people refer to their performance problems as ‘lag.’ Maybe I’d feel better if there was a clear distinction between internet latency and local computer performance..

Lag is too general a term to start with

As you know any delay in normal operation is considered lagging / falling behind, whether this is due to imperfect software or latent data transfer. lag in telecoms is considered any hit to expected bandwidth performance (which could be due to a number of issues) Latency actually lags bandwidth, even low latency. lag in a computer system can also be down to a number of different issues (like having to wait for something may not just simply be about how fast an interconnect is, the cpu may be waiting on the memory to return its value).
Distance effects latency and contention and latency effect actual total bandwidth, which is true for both local data lines associated with your computer system and telecommunication systems and lines

A computer system and the internet are both prone to contention and latency in the same way. Now For those reading this that dont understand latency and contention here's about the simplest way i can explain both.

Latency: is simply a delay between action and reaction. for the internet latency is nearly always described as the time delay for a round trip packet, for example playing an online game the latency would be the time it takes for your requests to talk with and negotiate with the game server and then for that request to return back to you in the form of an action (simply you move forward in-game and you and everyone else percieves that you move forward, some people will see this faster than other due to latency)

Contention: for want of a better word would be the max potential load on a system
for example trying to stuff a 10GB file down a 1Mbit line, you would have contention, you can probably notice this effect when transferring larger files from hard disk to hard disk, for example transferring a 1MB file from hard disk to hard disk for arguments sake takes 0.5 seconds. theoretically a 1000MB file should take 500 seconds, but due to latency and contention its never practically that, its why SATA II harddrives dont actually have a consistent 300MB/s data transfer rate. The more efficient the system the less you have to worry about contention and overhead allowance though

If your computer is noticably lagging when it shouldnt be its easy diagnose. you dont have enough processing power/ or available memory to do many things at once or maybe your running windows and a program hangs and screws up normal function buy not releasing or tying up a shared resource, (thankfully vista isnt badly plagued). If your internet is lagging when it shouldnt be, its either a problem with termination; someone else's computer/server. switching hubs, your ISP's services (which includes theyre swtiches, server load, distance etc,) etc. etc.

Lag is lag no matter what your referencing