Default Thread Pool Size in various .NET Framework Versions

The default upper limit of threads that the Thread pool will create by calling ThreadPool.SetMaxThreads;

• 1023 in .NET Framework 4.0 -32-bit environment
• 32768 in .NET Framework 4.0 - 64-bit environment
• 250 per core in .NET Framework 3.5
• 25 per core in .NET Framework 2.0