Sadly, this is not the case for resource-challenged older machines. They ARE SLOW. And we wait for them.
But there is something, or there are a few somethings, you can add to your computer to extend its life by a few years.
You can add memory. This is the biggest bottleneck for 3 year old and older machines -- not enough memory to run current day programs without paging to disk, a very slow process that can be eliminated by adding more memory.
Many of these older systems have only 512K or 1 MB of memory, but most will have 4 memory slots that will accept 1MB of memory per slot, for 4 MB total, which will turn an older 512K machine into comparative race car (so to speak).
And it is EASY to swap out the older memory cards for the newer ones, and it is easy to find and order the correct memory for your computer. You just have to know the make and model of you computer and how much memory it has to begin with.
Most computers, when they boot, show the installed RAM as one of the first screens they display, and any Windows computer will tell you how much RAM it has or recognizes by clicking on the System icon in the Control Panel window. If that amount is less than 2 GB and your machine is too slow when you are loading multiple programs or surfing the web, it is almost certain you can speed up your machine by adding memory.
System will also tell you your processor type -- if it is a Pentium 4, Pentium 3, Celeron, or earlier processor, there may not be much you can do, since these are slow CPUs and their motherboards will likely not accept much more memory.
But let's say, for example that you have a Dell Dimension 9100 computer from a few years back. That machine usually came with 1 GB of DDR 2 RAM in 2 cards, but can accommodate 4 X 1 GB cards of 4 GB total, which can be purchased reasonably, either from Dell, more expensively, or from 3rd parties, at lower prices.
To see what's available for the 9100, just Google "Dell Dimension 9100" memory, and see what results you get.
In this case the top 3 results are from Crucial, Dell, and 4AllMemory, all reputable suppliers I have used with success. They list the memory that will work with this systems, and in some cases there are different specs for different prices, but all will work.
Dell has the 1 GB modules for $34.95 ea -- I need 4 modules, so I'm going to pay a little under $140 for what I need, and which, while not a negligible sum, is a fair price to pay to get your computer to painlessly take you into, say, 2013 or 2014.
As for taking out the old modules, most slots have latching clips at the end and are to be pulled gently away from the modules until they release, at which point the module can be lifted out.
The new modules go back in the same way the old ones came out and are directional -- there is a little slot in the bottom of the module that needs to line up with the plastic tooth in the slot. Press down on the top of the card until the side-latching clips click back into place.
Do be careful to work in a low static environment with decent humidity, say 40% or above. That's hard in the winter! And do hold the memory modules by the sides and not the bottom contacts.
You do have to be willing to open the case and do a little out-patient surgery on your computer, but the time required is very small, 10 minutes max, and the reward is great! Speed!