For a long time now , a standard piece of advice to authors of MSBuild .targets and .props files is to make sure you add your file path to the property $(MSBuildAllProjects) . This is because MSBuild checks the paths listed in that property when it wants to determine whether a project file has changed and needs to be rebuilt. So if you wanted projects that use your .targets or .props to be rebuilt when your file is updated or edited, you added your full path to that property.
However, there were three problems with this:
The end result was that on some larger solutions we’ve looked at, you end up with a non-trivial percentage of the managed heap devoted to just this one single property. And the thing is that 99% of the time we only really care about one file in that list — the file that was last modified, since that’s what MSBuild is going to check against.