ErrorAnnotator: Noticed slowness on large directories (but not on debug mode)

[albilu]

Description
Slowness noticed on large directories ex: with this repo https://github.com/timboudreau/netbeans-contrib
with the Annotation Provider implementation (provides decoration: badges for Packages and Errors in files/folder)

The weird part is that there is no such behavior when in debug mode

Starting point: https://github.com/albilu/netbeansPython/blob/master/src/main/java/org/netbeans/modules/python/indexing/PythonErrorAnnotator.java#L36