The reason is that searching for a class in a VirtualFile-based
directory (i.e. in a package) happens for O(|amount-of-files-in-dir|),
and it may be rather crucial for packages with a huge amount
of classes
Note that it was checked that the cache should not take a lot of heap
since we call findClass only for really existing classes:
see org/jetbrains/kotlin/load/java/lazy/descriptors/LazyJavaPackageScope.kt:48
For example, there are no more than 10k classes for the whole
intelliJ project (but the cache is flushed for each module)
Denis Zharkov
aba8b4e2ba