As the title, Which is faster? Intellij built-in build system vs Gradle. And which one should i use?
The compilation speed is the same. The difference is in incremental build and caching. Idea allows to use partially compiled project, meaning it recompiles only those parts of code that are related to currently executed code. On one hand it is much faster for debugging, but on the other hand sometimes it produces a very bizarre behavior during debugging and run.
Total recompile feels faster in gradle. And of course gradle build is much more reliable.
They both use JDK tools for compilation so there should be no big difference. Incremental compilation can speed up the process, but sometimes can produce troubles (differently in different build tools).