Anti-Virus Software
Continua CI invokes programs such as Subversion, Mercurial, Git, MSBuild etc. that create or modify large numbers of files. Anti-virus software is known to cause major performance problems with these programs, particularly with writing to the file system. This has an impact on repository throughput on the server when pulling down changes from a remote repository, and build performance on the agent when syncing the workspace or cloning the repository cache. This also has an effect when exporting the source to the build workspace from the agent's repository cache. In our testing with Mercurial, a clone that took 2 minutes to complete with anti-virus disabled, took over 14 minutes to complete when anti-virus was enabled.
AV software can also cause application errors, such as "access denied" or "file not found", when invoking compilers and version control clients.
We recommend that you add folder exclusions for the data share folder on the Continua CI server machine, and the agent workspace folder on the agent machine.
Continua CI cleans up the Server and Agent workspace folders periodically, however after adding AV folder exclusions for them, we recommend adding scheduled AV scans for those folders during quiet periods (typically overnight).
If you are using the bundled PostgreSQL database engine, then you should also add a folder exclusion for C:\ProgramData\VSoft\ContinuaCI\PostgreSQLDB to avoid database errors (AV software can cause read timeouts and issues with backing up the database).
Note that some anti-virus software, even when folder exclusions are added, can cause increases in CPU and I/O usage.
Indexing Services
Windows Indexing Service can cause file locking issues, and the Server and Agent workspace folders should be excluded from the index, or the Index service disabled (it is of limited use in server environments).
You should avoid installing version control clients like TortoiseSVN and TortoiseHG on the server or the agent, as these programs do background indexing (for icon overlays) and can also cause file/folder access issues.