Assembly Definition (asmdef) Workaround for infinite compilation due to misconfiguration is a serious technical bug that frequently occurs in real machine testing and rendering pipeline extensions. Explanation of the solution to the delay in which the Unity editor freezes with "Compiling..." for tens of seconds every time a single character is rewritten in a C# script.
Specific symptoms of the problem
Every time I rewrite one line of a script file (.cs), save it, and return to Unity, the "round and round mark (compilation indicator)" at the bottom right keeps spinning for 10 to 30 seconds or more, and the entire editor freezes completely and no longer accepts any operations.
Real-world analogy: Every time you modify one character (one code) in a dictionary, thousands of pages of the entire dictionary are printed and rebound as a book from the beginning, which is a huge and wasteful printing factory.
Since all of the project's code is in one gigantic scroll (Assembly-CSharp), even just changing the last character requires censoring and rewriting the entire scroll from beginning to end. By separating the books into "independent thin booklets (individual assemblies using asmdef)" for each folder, you only need to reprint the corrected booklets, and other beautiful booklets can be reused as they are, reducing the waiting time to an instant (several milliseconds).
Figure: Overview of the defect occurrence mechanism and resolution approach for workarounds for infinite compilation due to Assembly Definition (asmdef) configuration errors
Assumed causes and detailed mechanism
This is because all the scripts in your project are bundled into a single giant standard DLL (Assembly-CSharp.dll), and even a single character modification causes the CPU to recompile and relink all thousands of unrelated script files from scratch every time.
Solution approach and optimization procedure
Cleanly subdivide the folder structure by function or system (e.g. core, UI, external libraries, etc.) and place "Assembly Definition (asmdef)" assets in each folder to completely separate compilation units into separate independent DLL files.