MAK ONE Product Support Knowledge Base    

Performance Issues caused by the Fault Tolerant Heap (Windows)


Microsoft Windows has a subsystem called the Fault Tolerant Heap (FTH), which is designed to protect application users from unstable programs. In the world of computer science, a common cause of application instability is the incorrect usage of heap memory. Applications read and write data into system memory using address pointers. When an application gets the wrong address for a pointer and reads or writes to that bad address, the application can crash. The Microsoft Fault Tolerant Heap protects applications by validating every address that the application attempts to use. While this protects an application from crashing when a bad address is accessed, the constant validation also significantly slows down the access. For real-time applications that slowdown can be significant. In fact, it can slow down an application to the point where it is not usable.

In an effort to "fix problems for you," Microsoft will automatically tag your application for monitoring by the FTH if it crashes enough. Once tagged, your application will slow down significantly automatically. For developers using MAK Products and building plugins, these crashes are often frequent, and applications are often tagged for the FTH.

Affected MAK Applications

All MAK One applications are affected.


Moderate - running with the Fault Tolerant Heap does not affect application stability negatively. In fact, it may improve stability. However, application performance will be significantly compromised.


Microsoft Windows 10 and above.

Does not impact Linux.


Applications can be cleared from the FTH. To learn how, please read:

ST Engineering

ST Engineering