As of today, Intel CPUs are much better.
A simple benchmark (Matlab, data processing, four different steps in processing), between two PC's:
- AMD A8-6500 @ 3.5GHz (no OC): step 1 lasts 1 hour, step 2 four, step 3 ten minutes, step 4 half an hour
- Intel Core i7 4820K @ 3.7 GHz (new PC, no OC): step 1 lasts 3 hours, step 2 nine, step 3 and 4 combined last less than five minutes
AMD seems to win in total time (4.5 vs 12), but this is is not a good measure of performance here. If I combine this with the price of the processor (€95 vs €330), or the power usage (65W vs 130W), AMD wins massively. On the other hand, a different method of processing the same data makes the AMD take around two days (!), while the Intel does it in two hours. It heavily depends on the type of processing, and DF seems to favour single thread performance, which means Intel wins.
but it would primarily test the performance of minecarts and mechanisms
Yes, but the signal (minecart and mechanism performance) to noise (everything else) ratio is quite nice here, meaning we can somewhat separate these types of load from the rest. Similarly; a fort with twenty mist generators would test the type of load liquids impose.
While not perfect, this might be helpful to people wondering if their computer will run DF. Or people wondering if 3x expensive, faster RAM is worth the improvement in their case.
That is the best we can hope for, I think; it would be waaaaay too much work to set up a load of testing fortresses, let them run on different PC's, collect some measure of performance, and do some serious data mining to figure out what influences what. What Miuramir said is the most helpful:
My recommendation for a DF system varies somewhat as we find out more info on DF and technology changes, but is usually close to:
1) Figure out the best cooling system that you are willing to put up with (in the case of desktops), listen to, and/or carry (in the case of laptops). Laptop performance is almost entirely cooling dominated, and single-core sustained turbo ratings can be significantly different on a desktop with better cooling.
2) Pick a motherboard and memory that offers the best GB/sec sustained transfer rate from the main memory to the CPU that you can budget, and can be adequately cooled by the solution from step 1. You want at least 4 GB of memory, and preferably a bit more; more than 8 GB isn't going to help current-generation DF any, but might someday.
3) Pick the best current-generation CPU for single-thread performance under sustained load, that has at least two real cores, while cooled by 1), that is compatible with the motherboard and memory from 2), and that fits your budget. (While DF is single core, you want at least one more, so that the OS and so on doesn't cut into DF's time.)
4) Give it a good power supply with a high efficiency rating and enough headroom to handle everything cleanly.
5) Accessorize with everything else you need; most of the details are of low importance for DF's performance, although considerations like input devices and monitors can be important for the user experience.