MSBuild Performance Guidelines

MSBuild evaluates and builds thousands of projects in enterprise solutions. Performance is an architectural concern, not an afterthought.

Guiding Principle

Profile before optimizing; measure, do not guess. Use BenchmarkDotNet, the evaluation profiler (/profileevaluation), or ETW traces to identify actual bottlenecks before optimizing.

See evaluation-profiling.md and General_perf_onepager.md for profiling tools.

Allocation Awareness on Hot Paths

The evaluation and execution engines process millions of operations per build. Unnecessary allocations cause GC pressure that compounds across large solutions.

Rules

1. Avoid LINQ in hot paths. Where, Select, Any, First all allocate enumerator objects and delegate closures. Use foreach loops instead.