Find All is deadly slow

Description of the Issue

Find All in current document for large files takes too much (minutes, not seconds!)

Steps to Reproduce the Issue

1. open for example this huge file workshop.zip
2. 'Find All in current document' for ":" (443218 matches)
3. repeat the same search at point 2 multiple times

Expected Behavior

Find and mark all occurrences in a few secs

Actual Behavior

Can take more than 2:33 minutes on i7-8750h, 32GB RAM. Can also freeze forever sometimes randomly on repeat.
Same thing on other programs like 'CudaText' is almost instant, on 'NotepadNext' takes 2 secs, on 'Geany' takes less than 8 secs...