Project build times can be much longer when building a project with IL2CPPA Unity-developed scripting back-end which you can use as an alternative to Mono when building projects for some platforms. More info
See in Glossary. However, there are several ways to reduce the build time significantly:
Use incremental building
When using incremental building, the C++ compiler only recompiles files that have changed since the last build. To use incremental building, build your project to a previous build location (without deleting the target directory).
Exclude project and target build folders from anti-malware software scans
You can improve build times by disabling anti-malware software before building your project. (Testing by Unity Technologies found that build times decreased by 50 – 66% after disabling Windows Defender on a fresh Windows 10 installation.)
Store your project and target build folder on a Solid State Drive (SSD)
Solid State Drives (SSDs) have faster read/write speed, when compared to traditional Hard Disk Drives (HDD). Converting IL code to C++ and compiling it involves a large number of read/write operations. A faster storage device speeds up this process.