ChemDraw is experiencing slow performance issues after installing the recent Windows 10 updates in February of 2021 (Version 2004 Build 19041.804, Version 20H2 Build 19042.804, Version 1809, Version 1909).

ChemDraw is experiencing slow performance issues after installing the recent Windows 10 updates in February of 2021 (Version 2004 Build 19041.804, Version 20H2 Build 19042.804, Version 1809, Version 1909).

Performance related issues have been noted after installing Microsoft security update (KB4601319) and other cumulative updates containing the same KB for Windows 10 operating system versions 2004/20H2, 1909, and 1809. Performance issues include increased screen lag or choppiness, problems adding bonds, and cutting/pasting/moving of structures. The MS update includes the GDIPlus.dll file which affects font caching while running the ChemDraw application. After uninstalling this or other related cumulative updates, the performance issue is resolved.

Microsoft has authorized a mitigation file process (KIR) to be distributed to all users encountering the ChemDraw performance issue. The KIR rolls back the GDIPlus.dll functionality to its previous version. Future MS updates will not affect it as long as the group policy settings are set to "disable" for the offending KB. For a copy of the Microsoft Windows 10 Known Issue Rollback (KIR) instruction document, contact Support using the website listed below. The KIR installation files are found at the following locations:

Windows 10 (2004 & 20H2) Known Issue Rollback 040221 01.msi
Windows 10 (1903 & 1909) Known Issue Rollback 040221 01.msi
Windows 10 (1809) & Windows Server 2019 Known Issue Rollback 032321 01.msi

1. Download the KIR group policy MSI files for your OS to the local machine.
2. Run the MSI file that corresponds to the OS version requiring the KIR.
3. Note the ADMX file installed by the MSI file in the %systemroot%\PolicyDefinitions directory that introduced the regression. For example, the 2020 10B KB that introduced this regression on the 20H2 release of Windows 10 was KB4580364. Hint: Configure new files to appear at the top of the file viewer being used.
4. Run the GPEDIT command. Locate the Policy Setting for your OS and set it to "Disabled".

Known Issue Rollback (KIR) tool allows 1809 - 20H2 customers to leave 2021 2B and superseding updates installed until a resolving fix becomes available. The KIR, in this case, temporarily disables the specific code change that cause slower application performance until a resolving fix becomes available. Once the update that resolves the issue is released, the policy will be ignored and the machines will progress normally when installing updates.

This is addressed in ChemDraw point fix 18.1, 19.1 and 20.1 as well as the current version.  Earlier versions will not be ported and will need to be addressed through the Microsoft KIR, as addressed above.