Can this LinQ statement made run multi threading - using more cpu cores

Question

I have written the below linq statement. But it takes huge time to process since there are so many lines. My cpu has 8 cores but only using 1 core due to running single thread.

Answer 1

There are rooms for performance improvements before resorting to AsParallel

HashSet lstAllLines = new HashSet(
                                File.ReadAllLines("AllLines.txt")
                                    .SelectMany(ls => ls.ToLowerInvariant().Split(' ')));

List lstBannedWords = File.ReadAllLines("allBaddWords.txt")
                                    .Select(s => s.ToLowerInvariant())
                                    .Distinct().ToList();

List lstFoundBannedWords = lstBannedWords.Where(s => lstAllLines.Contains(s))
                                    .Distinct().ToList();

Since access to HasSet is O(1) and lstBannedWords is the shorter list, You may even not need any parallelism (TotalSearchTime=lstBannedWords.Count*O(1)). Lastly, you always have the option AsParallel