SEP? Not forgetting it's close cousin
Bistromathics
The sort of mathematical rules that come into play when you try to divide up a restaurant bill. No matter how you do it, it never tallies with the amount on the invoice.
The problem with performance management is that no matter how you do it, it always fails. You monitor all your services. Identify a bottleneck. Spend ££££'s to fix it. Sit back in the glow of a job well done. The phone rings and it's users complaining about the NEXT bottleneck, now that the original one has been relieved.
Bottlenecks are like traffic lights: as soon as you get past one set of delays, you get a little further and the next one gets you.
So the net gain of the ££££'s spent is a small, imperceptible and soon forgotten benefit - whereas the cost is a monkey on your back forever. Each time you ask for more money to fix a performance problem, the bean counters remind your boss that the last attempt didn't work, or was only effective for a few sort weeks. Even if you have the experience to say "ah ha! we need to fix not only the prima-face problem, but all the structural issues behind it" and propose a cost-case to do it, you usually find that the problem goes so deep, the costs are so high and the upheaval so intense that you don't stand a chance of getting it approved. Certainly not for the miniscule and intangible benefits you can only _estimate_ it will bring.
Even invoking the third law of project proposals: The higher the price, the greater the chance of success.
Experience has shown that the best way to deal with performance problems is to ignore them. Leave them until they either cause something vital to crash and burn OR that they start to affect the CEO's computer. (In that case, fix his/her's machine and maybe "have a quiet word" while you're in their presence.) However, to succeed in this strategy, it's vitally important that you do not have any responsibility for systems performance, capacity planning, service quality or any of the other buzzwords that could let someone legitimately ask "Why did you let this happen?". Provided you leave it long enough, and the performance melt-down is severe enough (and can be shown to be someone-else's fault) you can get practically anything you like to fix it - except, of course, a raise.
Just as with the restaurant and settling the bill, performance is something everybody has, but nobody wants to pay for.