Hardware recommendations

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If you are working with large street networks and a performing multiple route calculations, it may be of interest to use the best possible hardware for the job. Testing has shown that it isn't easy to give exact recommendations, but this is our ordered list of importance:

1.	Have enough RAM to avoid memory swapping.

2.	Fast CPU speed.

3.	Fast RAM access (high quality motherboard and system in general).

4.	Intel Duron and AMD Athlon are slower than Intel Pentium / AMD64.

5.	Multiple CPU's (requires multiple rwcalc objects to take advantage of them).

In order to have enough RAM, a quick rule of thumb is that each link in your street database requires 50 bytes of RAM. So with 1 million links, you need 50 MB RAM.

Doubling the speed of the CPU, doesn't make the calculations twice as fast, as the RAM will usually be a bottle-neck and the level-1 and level-2 caches of the CPU isn't large enough for most networks.

The functions IsoPoly2, IsoPoly3 and IsoPoly4 all requires a lot of RAM, when used with large street networks. Depending on the exact function parameters, this may be 3-4 time as much as the street network itself, i.e. another 150-200 bytes of RAM per link.

An example: 6.2 million links, IsoPoly2 function call with 3 drive time zones (2, 5 and 10 minutes) around 770 centers required 1.4 GB RAM (and took ½ hour). IsoPoly3 and IsoPoly4 are less demanding.