Take feedback, add section on COMPLUS_JitMinOpts

Author: BruceForstall

docs/testing-with-ryujit.md

@@ -105,7 +105,7 @@ To prevent any NGEN native image from being used, and force all code to be compi
 
 **Note** This setting applies to both the 32-bit and 64-bit JIT. Thus, setting this globally will affect all 32-bit .NET applications as well. This is particularly true for **Method 2: environment variable**.
 
-**Note 2** NGEN provides significant performance improvements to .NET applications. Disabling the use of NGEN will cause the perfomance of .NET applications to be significantly worse.
+**Note 2** NGEN provides significant performance improvements to .NET applications. Disabling the use of NGEN may result in significantly slower application startup times.
 
 * **Method 1: per-application config file**. Add the following text to the `<app>.exe.config` file. Create
   the indicated sections if they do not already exist.
@@ -177,7 +177,20 @@ In this case, the annotated `add` function will not be optimized. You can see mo
 
 This is only effective in solving a code generation problem if the incorrect code being generated by the JIT is due to optimization, as opposed to being due to unoptimized code generation.
 
-Note that this method applies to all .NET JIT compilers.
+**Note** This method applies to all .NET JIT compilers.
+
+Disabling optimization of all functions
+=======================================
+
+While troubleshooting, it might be useful to determine if *any* JIT optimization is causing problems. Instead of using the above `MethodImplAttribute` method above, you can set a single environment variable to disable all JIT optimization. Set this variable:
+
+        COMPLUS_JitMinOpts=1
+
+and run your application.
+
+Note that when you run your application under the Visual Studio debugger, it disables JIT optimization by default, to improve the debugging experience. You can read about that [here](https://msdn.microsoft.com/en-us/library/ms241594.aspx).
+
+**Note** This method applies to all .NET JIT compilers.
 
 Additional Notes
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