Rendering: PIII vs P4

[duderender]

I am working on a rendering, and I've noticed that the rendering times are hugely different from a PIII-733 Mhz and a P4-1.8Ghz. Obviously, the P4 should be faster. However, should it be almost 2 times faster?

My image (see below) utilizes raytraced everything (ray recursion 8), radiosity (1 bounce), enhanced low anti-aliasing.
p4 renders image in: 7min, 46secs
pIII renders image in : 18m 22secs

as you can see the p4 is: 2.36 times faster. Perhaps the numbers are correct, but I was hoping there was something I should look for to speed up my renders using the pIII.

http://members.shaw.ca/duderender/goggles/p4render.jpg
http://members.shaw.ca/duderender/goggles/viper-image_06oct_03.jpg

[garg]

LW 7.X is optimized for P4 so it work a lot faster with P4 processors. Beside trying to overclock a bit your P3 you can't do a lot.

Alain Bertrand

[Lynx3d]

Yea the magic word is SSE2...

The Pentium-M (the CPU of "Centrino" notebooks) is a tweaked PIII with SSE2, larger cache and some smaller optimization, and according to Blanos the 1,6GHz is up to 40% faster than a hypotetical PIII 1600 (i just devided the times of a PIII 800 by 2).
My Centrino Notebook also clearly beats my slightly higher clocked Athlon XP, the former FPU-Champion...
Athlon 64 also has similar advantage over an equally clocked Athlon XP.

And LW seems to be the only (?) renderer that only gets a major boost from using SSE2...neither Max nor Cinema4d (Cinebench) showed such a difference when they optimized for P4, however both get up to 20% boost with Hyper-Threading, while LW is almost "immune" to HT from all scores i've seen so far...

Whatever, with SSE2 optimization, FSB 800 and Hyper-Threading did a lot to help the P4's initially very poor per-MHz performance compared to other CPUs (but other CPUs developed aswell, Athlon FX and Pentium-M squeze out much more per clock, however both are limited to much lower clock speeds obviously)

[duderender]

Lynx3d,

Thanks for the insight!

So as it stands now, what is the best buy for a new processor? The AMD64 sounds very tempting but it is very pricey.

I am debating on a laptop or desktop, so any opinion is appreciated.

[Lynx3d]

Hm...if you really want to be mobile you'll want a Centrino anyway, it's quite a weight difference between a P4 notebook and a Centrino notebook with same battery time...

According to Blanos the 1.6GHz scores very similar to a P4 2.2GHz (and that should be true for most applications), 1.7GHz is the fastest currently.

Otherwise, i'd get a P4, the faster the better obviously...Athlon 64 would be nice, but currently it's not faster than a P4 in LW, but expensive. Think it's not worth beeing an early adopter before Windows for AMD64 is out (unless you're using Linux a lot anyway) and the chipsets/boards are tweaked, more boards are out etc...