Forums  /  Dune series  /  Dune  /  DOSBOX CPU Cycle speed

Hello everyone
Just a short video to show the difference between playing "default" and set the DOSBOX cpu cyle to "Max" performance

as you can see the time gain is real, especially in a "menuing" game like Dune
Default vs Max :
Room change : +18 frames
"Loading" map screen : +19 frames
Dialogue box : +23 frames


I tried to play at 30000 cycles, but it's a bit too much for my computer, it lags sometimes.
I'm a bit frustrated to be disqualified at Dune speedruning just for technical reasons.
Moreover, at 30000 cycles the game is way faster than it was in the 90s. It feels different, and that bothers me. We may speedrun games but we shouldn't change the way the game behaves.


Hey !
Sorry I played at 30000 thinking it was not a problem for the community ! But If you have a technical issue with the cycle speed we definitly need to fix that value. I know last time I said "why not 10000",but nothing was official so I decided to run at 30000 thinking it was not a problem for you.

That's sad you can't play at decent cycles 🙁 maybe DosBox is not the "optimal" way to emulate this game.
What's your CPU ? I have a i7 6800k and 30 000 run flawless.

I cleary don't remember how fast it's supposed to run... so it's difficult for me to say "the game is not running at the original speed" and even if "original speed" exist, which is wrong I guess, because even in the 90's we had different CPU changing the speed of the game etc...

After some digging I found a "40000 cycles" is equal to a standard 486 processor and should be used in a TAS recording. (source : http:/​/​tasvideos.​org/​DOSBox.​html)

We can also look into this page : https:/​/​www.​dosbox.​com/​wiki/​Performance
for example : "486 66MHZ CPU = 26800 cycles"
It's weird you can't play at 30000, according to the wiki a Pentium III 1.0Ghz can emulate a 486 66Mhz

It seems 40 000 cycles is a standard for other dosbox game, look at the rules for Jazz Jackrabbit game :

"Do you use DOSBox? Please fix cycles to 40,000 for comparable loading times. (Edit dosbox.conf: core=auto, cputype=auto, cycles=40000. Or type "cycles 40000" into a running DOSBox before starting Jazz.)"

Could you try with this settings to test if you have lags etc.. :


Sorry to bother you with this stupid config file 🙁


My technical problem is not for emulating the game, it's for emulating and streaming at the same time. It's OBS that takes the majority of my computer resources.
For more than a year, you ran at 10000 cycles and I didn't know. When I followed suit, and beated your time, you one-sidedly decided to change your settings to 30000.
And now, if I understand well, you want to change again. Please understand it's not possible to change all the time.
Your source on also states "Use the largest possible value that you think makes the game run more fluently, but not larger." That's to avoid distorsion.
According to this source https:/​/​www.​pcgamingwiki.​com/​wiki/​Dune floppy disk game requirements are a 286 processor. That's 6MHz to 20MHz, so it corresponds to 6000 cycles to 20000 cycles in DOSBox. Thus it mustn't be played faster.
I say we should keep 10000 cycles max for consistency with the other categories, and because the majority of the runs were made with these settings.
In any case your last run at 30000 cycles is above reasonable limits and should be cancelled.


Hey !
The main goal with this topic is to demystify the approximation we give on the speed of this game and also share to the community what I found behind the game/emulator, provide a universal way of playing for both veteran player and newcomer and make it acessible for all type of player whatever the hardware they use.

Just wanted to figured out what other speedrun DOSBOX community do with their game and understand/explain why we should use a specific settings. I try to give an answer in a less aproximative way.

Sorry for the frustration generated, I do my research alone on my small free time and not communicate very well.

You can obviously delete my WR run If I don't respect the rule of the community.

We have now the information we need, "the original requierement", and even if I personaly prefer to play at the maximum speed the game allowed us to play, we should use the original requierement provide by the developer.

20000 is a good compromise and should work for on every hardware.

Just for fun, there is a small Update about my calculation method on the first video, It seems the opening map sequence (even the dialogue box maybe ?) frame counter is variable (lol)
Here is my mesurement with 5 record of each cycle :

10000 Cycles - Min : 33 | Max : 36
20000 Cycles - Min : 31 | Max : 33
40000 Cycles - Min : 30 | Max : 31
80000 Cycles - Min : 27 | Max : 29

Above 100,000 cycle the game is laggy so I presume there is a limit the game could be played but I think is also depending on the main CPU we use...

My next step is to run on real 90's Hardware ! 🙂


I'm very interested with your tests in a real hardware. I remember playing Dune on a Pentium I back in the days, and I remember it a little bit slower than 10000 cycles. But hey, it was a long long time ago.
Let me know when you have some results.


Given all the information we have now on game technical requirements and DosBox performance, we can now decide that it is reasonable to limit the Dosbox emulation speed at 10000 cycles max.
Unfortunately, that cancels your last run.