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This article relates to the fractal program "Apophysis" (Apo), but may also be relevant to other image rendering programs.

In Apo, there is a setting in the OPTIONS menu where one can specify the number of rendering "threads" to use. This has a direct impact on the amount of rendering time an image takes to render. If set to OFF, the image will render as if it was using a single CPU. If set to 2 or 4, the image will render in much less time, because it has 2 or 4 CPU cores of which to take advantage.

People who have Intel CPUs, which have hyperthreading (such as some Pentium 4's), can set this option to 2 if they wish (DO NOT use higher than 2).

Don't know how to get an image in here, so here is the screenshot link showing this setting option.…

Hyperthreading (wanky marketing speak), basically means the CPU has "two threads" with which to perform its data processing (sort of like two CPUs). When set to 2, Apo can use 100% of the CPU and thus cut rendering time. However, this may not be the best option with systems which generate a lot of heat and are not efficiently cooled (some laptops/notebooks may be an issue). It can be a trade-off between less render-time, OR a processor working at half its capacity and therefore producing less heat. System crashes can be a result of the processor over-heating.

If you have a newer system with either an AMD or Intel Dual-core processor, or for those fortunate people who may have a quad-core, then you should definitely set this option to correspond with the number of cores in your processor. There should be no problem with over-heating, as these newer processors have more efficient thermal designs than the older Pentium 4's.

I am running a Pentium 4 which has hyperthreading and I have set the multithreading option to 2. It can sometimes halve the rendering time, but always results in a substantial reduction.

The other thing I notice is the drop-down box below the multithreading box, which relates to both your CPU and operating system. Newer CPUs (from around mid-2003 for AMD and later for Intel) are 64bit. Prior to this they were 32bit. If your CPU and operating system are both 64bit, then I also suggest choosing the 64bit setting. I don't know the impact of this (mine is 32bit), but you will find out once you switch between the 32 and 64bit settings.

Here is the screenshot link showing this setting option.…

To test the impact of changed settings, you need to commence a render on the old settings. At the bottom of the render screen, the "estimated time to complete" will appear. Take note and STOP the render, then close it. Go back into OPTIONS and change the settings then commence the same render. Now you should see the time to complete has considerably reduced.

Steve Knorr
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Fractalion Featured By Owner Mar 22, 2015   General Artist
Thanks man :)
Darkestnightmare Featured By Owner Jul 11, 2013   General Artist
When I try and render one of my old fractals it ends up looking practically see through. Why is it doing this all of a sudden?
Felewin Featured By Owner Apr 20, 2013  Hobbyist Digital Artist
It's too bad multithreading doesn't apply to previewing. We spend more time previewing that rendering!
3lectr0lite Featured By Owner Feb 1, 2013  Hobbyist General Artist
I chose to use my quad core with this information, still works fine! I don't recommend it, though. All I should point out, is that this will make renders easier to handle (I have had to wait 14 hours because I never chose Threading:4!!!)
Analog-X64 Featured By Owner Jun 25, 2011
I am using apophysis 7x 15 on win 7 / 64bit I can set the Multi-Threading but I do not see the 64-Bit option. I have a Core 2 Quad Q8300 CPU.
duggym122 Featured By Owner Jun 15, 2011  Hobbyist General Artist
Huge help. My computer at home works great (probably better once I get back and try this), but I do a few renders a day at work on my workstation and they don't go quite as fast as at home. Got a render to go from 1305:18:49.54 to 2:17:25.88
Psysoul Featured By Owner Oct 16, 2010  Hobbyist Digital Artist can choose 8 threads for intel core i7 // 4 cores, because it also uses hyperthreading (well, if it's enabled in the BIOS).

Result: super good rendering time.

I am using apophysis 7x on win 7 / 64bit.

32/64 bit doesn't really change rendering time, but 64bit seems to create a bit more lag for mouse etc..i am not sure.

interesting that 32/64 create a different file (not the same size).
Drummerboy08 Featured By Owner Oct 26, 2009  Hobbyist General Artist
Very helpful! i have been under the impression that it simply couldnt render using both cores of my CPU, as my CPU clock had only ever been able to get to half. My renders now go so mcuh faster, and it makes it easier to work with a higher res preview, or zoomed-in fractals.
bernie-saw Featured By Owner Jul 13, 2009   Photographer
My Apophysis doesn't have that option. I have version 2.02
katdesignstudio Featured By Owner Apr 11, 2009  Professional General Artist
This was wicked useful, thank you!
Xyrus-02 Featured By Owner Mar 9, 2008  Professional Digital Artist
This goes to favourites because it's very useful stuff. Thank you =)
starsofglass Featured By Owner Feb 12, 2007
I just upgraded from 256 mb ram to 2 gb ram (dual core), and by comparison my rendering time only halved. And that was by switching from 32 to 64 bit (after reading your journal I'm a bit confused, because I have Windows Vista 32 bit, not 64 :) ). But anyway, setting multithreading to 2 does seem to halve the rendering time again, but more than 2 doesn't seem to do any more. Know of any other ways to speed up the rendering (without changing the quality settings)? I thought that having so much more RAM would speed things up more :(
zsteve Featured By Owner Feb 12, 2007
Ok, first of all, if you have a dual core processor which has 64 bit architecture, I don't understand why you would choose to run 32 bit Windows and not 64 bit. Second, if you *are* running 32 bit Windows, I also don't know why changing the setting to 64 bit in Apo reduces your rendering time, as I thought the operating system would need to be 64 bit. Maybe it is enough that the processor is 64 bit for this to happen, but I am just guessing.

My understanding, is that the multithreading number set in the *context of Apo*, equates to how many threads your processor can process at any one time. And in the case of dual core, each "processor" processes one thread, which means it can process two (being dual core). If you had a quad core processor, then you could choose the "4" setting. But again, I can't say to what degree this would have on rendering time, as I don't have either dual core or quad core processors.

Multithreading is actually more complex than this, because lots of software programs can run using multiple threads. This means a CPU may be processing multiple threads, regardless of the number of cores it has. But that's a whole other layer of complexity which you can read about on the Net.

Apo needs only a certain amount of Ram to be available for both the software and render. Depending on the quality and resolution of the render, it may need additional Ram to be available. Beyond that requirement, additional Ram is superfluous to the program, so you won't see any gain in time saved by having a greater amount of Ram available. It is only advantageous if you are simultaneously running Ram hungry programs. But 2gig is a nice amount of Ram to have in todays systems! :-)

A question... if you render something with the multithreading setting at 2 and 32 bit, and then render the same thing with the bit setting at 64, does the render time reduce further, or does it make no difference? I am just trying to understand whether the bit setting affects render time, or whether it is just the multithreading setting that influences the render time.
starsofglass Featured By Owner Feb 13, 2007
I did some testing today, and the results seem to be a bit different. I'm a bit confused by the different settings though, as there is a general options section where there are different "bit choices" but also the "bit choices" in the render window itself. I've been playing with both, combining in every possible direction with one of my fractals in particular.

To illustrate:
Multithreading off
internal buffer depth 32 bit integer:
-> buffer depth integer 32 integer: 6h19
-> 32 floating: 6h20
-> 48: 6h25
-> 64: 6h24

Multithreading off
internal buffer depth 64 bit:
-> 32 integer: 6h52
-> 32 floating: 6h19
-> 48: 6h25
-> 64: 6h24

Multithreading 2 seems to give more or less the same rendering times in every combination (3h20 more or less), although 64bit in the rendering window does require twice as much RAM. In all the cases, 100% of my CPU is taken though, which seems a bit strange, because the amount of RAM necessary is waaaay below what I have available. (Although running other programs at the same time doesn't seem to slow the rendering down much.)

As for having a 32 bit operating system... I had ordered a 64 bit one but they got one in the wrong language, and they only had 32 bit in the right language. And in the shop they said it didn't matter. After some research it might be best, apparently there are some problems with compatibility with 64bit Vista (only accepts 64 bit drivers, not 32 bit drivers), but I'm no expert. At the same time I am wondering if having a 64 bit OS would halve the rendering time again, but I guess we'd have to ask someone who has a 64 bit OS.

*sigh* I don't know enough on all this tech stuff, that's why I gave this overload of info :p After all the testing, still not sure on the settings except that multithreading is best :)
zsteve Featured By Owner Feb 14, 2007
The render window takes its settings from the general options window.
Bit settings don't seem to make a difference then, in your case anyway. Your testing seems to support this.
Multithread 2 also uses 100% of my CPU. But it also doesn't use all my Ram. I have only 1gig. But I can't run other programs simultaneously. I only have a single core CPU, so I have m/t set to off if I want to do something else while rendering.
I don't know much about the 64bit Op system. There is an awful lot of tech stuff to know and I don't know all that much either. I usually just learn as I go along! :-)
MadCatMk254 Featured By Owner Sep 20, 2008
I know this is a quite old post, but I figured I should let you know that Apophysis(3D) can take great advantage of 64bit Systems running on -pure- 64bit CPUs.

What I mean by pure:
"A CPU that is 64-bit internally might have external data buses or address buses with a different size, either larger or smaller; the term "64-bit" is often used to describe the size of these buses as well. For instance, many current machines with 32-bit processors use 64-bit buses (e.g. the original Pentium and later CPUs), and may occasionally be referred to as "64-bit" for this reason." (

In other words, you can enjoy the full capabilities of what 64bit technology has to offer in AMD proccessors.

This is also why rendering on an Intel Q6600 on 64bit Vista takes about 50 minutes (according to a test I had done), while a cheaper AMD (9850) did the exact same job under the same environment in about 35 minutes.
esintu Featured By Owner Feb 7, 2007  Hobbyist Digital Artist
that's really useful info, thanks :)
phoenix75 Featured By Owner Jan 5, 2007
Thanks so much, Steve. Great information and explained so well. I did know about the multithreading after searching the DA forum for some information. I was having trouble last month rendering and discovered about changing the setting. It was suggested to change to off so I have it there right now, but will see what 2 and 4 do. I bought this computer in 2004.

Anyway, thanks for looking out for all of us. :hug: :heart:
donnalorelei Featured By Owner Jan 5, 2007
OMG I had No Idea wtf the multi-threading option was all about ! ( vague notions of lines & threads wafted by now 'n then but that was it ) and it would never have crossed my mind that it related to cpu type etc. it makes sense of course, D'OH.

Thank You for explaining this so clearly. Rendering times will still suck for me coz I have such a slow old system :-( but at least now I know not to ignorantly pop the option up to 8 or something just for the hell of it!!
:D :hug:
zsteve Featured By Owner Jan 5, 2007
Good idea! I tried 4 when I first commenced Apo and my system froze. When you get yer new quad core, you'll know what to do. :-)
anjaleck Featured By Owner Jan 5, 2007  Hobbyist General Artist
Thanks for the info, Steve! I'm gonna have to play with this because I have an AMD and plenty of processor speed (1.8gHz) and memory (1 gig).
zsteve Featured By Owner Jan 5, 2007
Anj, unless it's a dual core AMD, it won't make any difference.. hugs!
anjaleck Featured By Owner Jan 5, 2007  Hobbyist General Artist
Thank you... I don't know if it is or isn't. I did have a dual processor machine for a while... but it took a dump on me and now this one is what I have.

I'll have to give it a try and see if it makes any difference. Probably won't. But my renders aren't that bad anyway. The most I've tied my machine up is 30 minutes... and that was for a super high quality one.

Hugs and love,
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