diff --git a/AGENTS.md b/AGENTS.md
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+++ b/AGENTS.md
@@ -2,12 +2,22 @@
 
 This repository hosts various libraries distributed as NuGet packages. Keep these links up to date so contributors and tools can easily locate them.
 
-Only the .NET SDK **8.0** is available in the execution environment. Use this version when building or running tests. When invoking `dotnet test`, do **not** pass `--no-build` because that leads to missing assemblies. Instead, specify the `--framework` argument matching the SDK available in the environment (currently `net8.0`).
+Only the .NET SDK **8.0** is available in the execution environment. Use this version when building or running tests.
 
-All `*.csproj` files should enable nullable reference types with `<Nullable>enable</Nullable>`.
-Indent code using four spaces or a single tab per level. Place one blank line after each closing curly brace of a code block, except when several closing braces appear sequentially. Always use braces for `if` and `else` bodies.
-All tests must use **xUnit** together with **FluentAssertions**.
-Implementations should be optimized for maximum performance even if that introduces some code duplication. Consider applying attributes such as `MethodImplOptions.AggressiveInlining` or faster alternatives to common operations when appropriate.
+## Implementation Guidelines
+1. All `*.csproj` files should enable nullable reference types with `<Nullable>enable</Nullable>`.
+1. Implementations should be optimized for maximum performance even if that introduces some code duplication.
+1. Consider applying attributes such as `MethodImplOptions.AggressiveInlining` or faster alternatives to common operations when appropriate. Another would be modulo "%" or division "/" operations, which could be often replaced with faster alternatives, possibly under specific conditions.
+
+## Running Tests
+1. When invoking `dotnet test`, do **not** pass `--no-build` because that leads to missing assemblies. Instead, specify the `--framework` argument matching the SDK available in the environment (currently `net8.0`).
+1. The tests run for a very long time, because there are 61_000+ unit tests for all the collections. Set timeout when running them to 15 mis.
+1. All tests must use **xUnit** together with **FluentAssertions**.
+
+## Source Code Formatting Guidelines
+1. Indent code using four spaces or a single tab per level.
+1. Place one blank line after each closing curly brace of a code block, except when several closing braces appear sequentially. 
+1. Always use braces for `if` and `else` bodies. 
 
 ## NuGet packages
 - [Recyclable.Collections](https://github.com/mlemanczyk/Recyclable.Collections)