How to improve Binding of Isaac performance?

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.

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".

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.

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.

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.

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.