BVH too long

Hi,
I’m modelling a Pagani Huayra and when I start rendering, BVH takes about 1.30 minutes if I turn off all subsurf in 3d view and verts counting go to about 350000, 3 minutes if turn on sub surf in 3d view and verts go to 890000.
For testing in an another file, I opened an empty scene and I linked (Shift-F1) a Mustang in an another file. The old one counts 240000 verts and BVH takes no more than 8 seconds, in the linked one verts count is 750000, without changing anything!
If I render my Cobra (775000 verts) BVH takes 9 seconds.

Ah time…why waste your life at all with 3D? You are complaining about waiting for 1.3 minutes?

If you modeled these other cars just do the same thing as you did before. If these faster rendering cars were made by someone else then study their technique and emulate it. Other wise you may need to consider that your model is flawed in some way and hanging up the system. Use the Outliner hide_render feature (camera icon) to solo specific parts of your model. Issue test renders to discover what part of the model is bogging down the system. Remove all subsurface modifiers you don’t need them when you are modeling.

Yes, you’re right, but what I can’t have is crashing every time.
Below here there’s what I mean.
If it’s helpful, my computer has an Intel Dual Core Duo E5400 overclocked to 3.45 Ghz, Nvidia Geforce GTX 660 Ti 2Gb SC+ 78 Mhz, 3GB RAM, Windows 7 Professional 64bit

the prosessor is bad, and 3 ram is REALLY really low. you chould consider to upgrade. not much is nessasary tho, only MB CPU and RAM. keep the rest.

3GB of RAM is what’s killing you. Your OS alone likely takes up close to that amount, so any time you’re starting to build a scene it’s not just building the BVH, it’s copying data to your swap partition before, during, AND after mesh synchronization and BVH creation. I/O speeds for the average hard drive are hundreds of times slower than direct memory access. Memory is dirt cheap, that would be my first suggestion if you’re serious about continuing with 3D work.

Yes, I know, 3Gb is too low, with 333 mhz of frequency is also the worst. For the CPU, it’s since 2006, but all in all it’s not so bad.
HD is maybe my bottleneck, 7200 rpm and 100 MB/s Writing-Copying, maybe a SSD would better.
For what said m9105826, I didn’t understand; yo wanna say that “because you have 3GB of RAM BVH must be calculate every time while if you have more RAM BVH mustn’t be calculate anymore”?
What brakes myself to update is the price. In Italy electronic components cost really more than other places as America.
Intel Core i7 4770 in NewEgg.com $309.99, in Italy $444 (converted by Euros).
Corsair Force LS Series CSSD-F240GBLS 2.5" SSD in NewEgg.com $187.99, in Italy $248.

Forgot this: I tried to use Windows Readyboost, the tool which use a USB to increase the RAM, so I tried with a 4 GB and I should get up to 7 GB of RAM, but nothing happened.
There’s the linked’s trouble, too, when I linked the car and geometry has tripled.

No, because you have 3GB of RAM BVH, mesh sync, and building must be copied to and from the hard drive multiple times which is killing your build times. Readyboost does nothing, that’s even slower than a hard drive. The root of your issue is your RAM. Your upgrade options for this issue, in order of importance are:

1.) RAM (need enough to store your OS, background apps, Blender, AND the whole scene copied to Cycles)

2.) CPU (although subdivision code is currently single threaded and done prior to export)

3.) Hard Drive (an SSD with a swap file on it would ensure that even if you went over memory speeds would stay reasonable)

Thanks m9105826, I’m breaking myself because for changing CPU I have to change the mainboard too.
How much RAM I have to add, 4-5 GB more are as well?