using var repository = new Repository(@"<repo_path>");
using var revWalker = new RevWalker(repository);
// Store commits in a cache to speed up multiple walks on same repository
var commitsCache = new Dictionary<ObjectId, Commit>();
 
revWalker.Reset();
revWalker.Sorting(CommitSortStrategies.Topological);
revWalker.PushGlob("refs/tags/*");
var commits = GetCommits().ToArray();
// Subsequent walk will reuse commits cache and internal RevWalker cache
revWalker.Reset();
revWalker.PushRef("HEAD");
commits = GetCommits().ToArray();
 
IEnumerable<Commit> GetCommits()
{
 while (true)
 {
 var objectId = revWalker.Next();
 if (objectId == null)
 break;
 
 if (!commitsCache.TryGetValue(objectId, out var commit))
 {
 commit = repository.Lookup<Commit>(objectId);
 commitsCache[objectId] = commit;
 }
 yield return commit;
 }
}