ClamAV x86/x64 Optimized Builds (English) 
Sunday, April 06 2014 . 09:31 AM
ClamAV is an open source (GPL) antivirus engine designed for detecting Trojans, viruses, malware and other malicious threats. It is the de facto standard for mail gateway scanning. It provides a high performance mutli-threaded scanning daemon, command line utilities for on demand file scanning, and an intelligent tool for automatic signature updates. The core ClamAV library provides numerous file format detection mechanisms, file unpacking support, archive support, and multiple signature languages for detecting threats.

I am building ClamAV from the original sources, to make freely available my optimized compiles. I am not modifying original code, but applying a different build chain to gather a better executables, in terms of native x64 support as well as regular x86; faster execution speed; smaller executable size; and lower memory footprint.
Of course, the rest of features, should be exactly the same as in official ClamAV.
To prevent any possible confusion, my releases are groupped under the ClamAVOpt name, as an acronym of "ClamAV x86/x64 Optimized Builds".

ClamAVOpt is totally free, both for commercial, and private usage.

Before reporting an error in ClamAVOpt, please make sure it is not inherited from ClamAV. If that is the case, you can report it in the official's issue tracker. You can see official changes in the official repository.


/Oy: Omit frame pointers.
/GT: Enable fiber safe optimizations.
- Compiled with /GF to pool common strings making executable smaller.
- Compiled with /Zp16 to get faster code when accesing data structures specially on newer CPU.
- /arch:SSE2: Enable SSE2 instruction set in x86 targets.
/GS-: Disable buffer security check.
- Compiled with /fp:fast to increase floating-point operations performance at the cost of some precision loss not noticeable on ClamAVOpt.
- ZIP package created with KZIP 14/04/2007 to reduce distribution size.
- Executables compressed with MPRESS 2.18.
- Using Profile Guided Optimizations (PGO) for all builds builds making libclamav.dll about 17% smaller and marginally faster.
- Based on latest ClamAV 0.97-133-gde8d667 (2011-08-02) sources.


- Generic x86 version (2.4 Mb. in ZIP format). Valid for Intel Pentium; AMD K6; Cyrix 6x86 or later.
- Generic x64 version (2.7 Mb. in ZIP format). Valid for OS running any x64 edition of Windows.

- Official ClamAVOpt's website:
- Official author's website:
- Official ClamAV's website: