Hi! I encountered a grep issue. For now, I use the older version of Cygwin (32-bit, W2k3) in my test environment (for nightly tests). I'm going to migrate to a  modern platform, Windows Sever 2016 or 2019. In the archive attached is a sample to reproduce the issue. Here is a simple script trying counting strings in data file (56 strings) according to a pattern (a pretty long one, auto-generated by test) in the corresponding file. Both data file and pattern file are from the real test. This counting takes about 25 seconds on the older 32-bit system and more than 2 and half hours on the newer one. See result_*.log files. In the last case grep fully uses 1 core of Core-i7 and consumes 2+ GB of memory. See screenshot. The pattern contains two serial 'http_host' sub-patterns. Maybe they lead to the issue because another similar tests have no such a problem and they do not contain such 'pairs'. -- Best wishes, Sergey.