I cannot go past level 3/4 because when I enter in rooms full of monsters the game start lagging a lot and controls do not respond at all or with a huge delay.

My configuration is not actually bad: Phenom X3 720 3Ghz + ATI 6850 HD + 4GB RAM

Do you have any idea how can I improve the performance of this game (that it is Flash based if I undestood well)? At the moment it is unplayable and very frustrating after first two levels.

UPDATE: I hoped that with DLC they took some times to optimize the code but unfortunately the problem is still there.

  • Did you try running some sort of resource monitor to try and see just what it is the game is hogging to cause the slowdown? I personally suspect this is some sort of software/hardware compatibility issue, as the game chugs along reasonably well on my aging 4 year old laptop (not to mention it runs just fine on my desktop, which I believe yours outspecs). – Aubergine Oct 6 '11 at 6:37
  • I have all other programs close, except Steam. I tried to open the task manager while having this lagging and delay issues and I saw that Isaac's process consume 40/50% of CPU. – Drake Oct 6 '11 at 7:21
  • My, my, I never saw it go over 6% at most. Did you try seeing how your computer handles heavy flash animations? This thing has my chrome at 25% CPU on my desktop (so effectively it grinds one entire core on my CPU). – Aubergine Oct 6 '11 at 16:46
  • @Aubergine That thing took my CPU to around 30% and it registered between 40 and 50 fps. – Drake Oct 6 '11 at 17:39
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    You could try this: forums.steampowered.com/forums/… – mordi2k Oct 8 '11 at 23:08

I saw this from another forum. The lag is akin to "walk on ice", so you will still move to a direction a few milliseconds after having released the directional button.

There is one setting in the graphic options that will solve that. Set the details to "Low". That is it, no more lag. It is probably related to flash overall poor performances. It changes the game from unplayable to "omg its soooo good".

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    Yes, "walk on ice" are the right words to describe it. Unfortunately my settings are already set to "Low", and I have the same effect. With a lot of luck yesterday I reached Mom but during the fight the effect was terrible and miserably lost. – Drake Jan 31 '12 at 12:12
  • The developer said it himself, he's added so much to the game that Flash just crashes. rockpapershotgun.com/2012/08/30/… – Slurpee Jan 22 '13 at 17:56

It's probably Flash hogging up your on-board RAM and CPU power.

The Phenom II has a CPU speed throttling and power saving feature called "Cool'n'Quiet", where it undervolts your CPU when under low load. Try turning this feature off in the BIOS and see if that helps your frame rates.

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    I was a bit skeptic about it, but I tried anyway. No results, from disabling Cool'n Quiet BIOS feature. – Drake Feb 1 '12 at 10:12
  • Are there any changes in improvement if you play in full screen mode? Also what resolution are you running at? – Krazer Feb 4 '12 at 0:14
  • I tried both playing fullscreen and in window. I try reduced also the resolution to minimum, but same effect. – Drake Feb 4 '12 at 0:31
  • By resolution, I meant screen resolution, not detail. E.g. 800x600, 1024x768; – Krazer Feb 4 '12 at 0:37
  • Are you on XP or W7? Try changing your performance to "Better Performance" in the "Advanced" tab under "System Properties" in Control Panel. – Krazer Feb 4 '12 at 0:46

From personal experience I found that the only way to get Binding of Isaac running smoothly is to play the steam version via wine. Neither running the windows version on windows, the windows standalone version in wine or the linux version on linux helped, but using the steam version in wine causes the game to run great. Every lag is gone, even setting the details to the highest possible value does not affect performance anymore.

  • It seems interesting, but I never used Wine on Windows, can you expand a bit your answer? – Drake Apr 12 '12 at 23:43
  • Oh, Wine on Windows? I'm not sure if that's even possible. – Wieland May 4 '12 at 8:32

The reason for the slowdown is not your computer, but the game itself. It's coded in Actionscript, which is designed for use in Flash files, so whenever too much happens the engine just can't handle it all.

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    You're not wrong, but this still doesn't quite seem to be the answer that the question warrants. – nine Sep 29 '15 at 20:01

To reduce the effect of this dreadful bug, make sure you play the game on 800x600 fullscreen mode, small window and lowest details setting.

To get rid of it for good: after running the game, press Ctrl+Alt+Del to invoke Windows Task Manager, select the Processes tab, find the Isaac.exe process, and right-click it. Choose Set Priority > Below Normal. Albeit counter-intuitive, this actually decreases the priority of the game engine process which allows for faster processing of key presses by Flash. This fix works for WotL v1.48 and the original BoI, and I posted this fix on the wiki.

Note that the game will still be slow (which helps you to avoid some shots) but it will react to keys immediately.


It's because the game is written in flash and flash can't handle the kind of stuff this game is trying to do. There's not much you're going to be able to do to fix this outside of waiting for the remake

  • Technically, it's more because this game in particular is poorly optimized. There are games in Flash which are performing perfectly for the same kind of demand, or more. – Gnoupi Jan 22 '13 at 16:57
  • I love this game but frustrated because I cannot finish it due to performance issues. I hope to upgrade my CPU soon or eventually wait the remake. – Drake Jan 23 '13 at 9:54
  • I'm in the same boat, I just uninstalled it because of the performance but wish I could have finished it.. I have an i7 2670 and that wasn't enough. Fine example of why it takes more than just a good idea and passion to make a game. If you have no f'ing clue what you are doing as a game design you can make the best game in the world and it's still going to be a crappy experience for all :( – unc0nnected Feb 13 '13 at 20:35

I managed to fix this problem by deleting the settings and cache in Control Panel > Flash > Advanced


going full screen solved my problem. runs super fast.

  • This is a helpful, but very brief answer. What kind of specs do you have? What kind of performance were you seeing before and after this? That would be helpful information to add :) – two bugs Jul 8 '16 at 14:24

Being that your CPU and GPU are more than powerful enough to handle the game, the only thing I could suggest as the problem would be your RAM.

The game is probably having trouble handling all the data for the enemies due to insufficient RAM.

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    Thanks for comment, but I have 4 GB of RAM (I updated my question now) and I have no other applications than Steam running in background. – Drake Feb 2 '12 at 16:47
  • In that case, I am unable to help you as I don't own the game so I can't test it for myself. – Ryan S. Feb 2 '12 at 23:52

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