IterationWithLinq.cs

public void ImportFiles()
        {
            var query = from f in files
                        where f.Extension.ToLower() == ".zip"
                        select new ImportContext
                                   {
                                       ZipFileName = f.FullName,
                                       Path = UploadPath
                                   };

            foreach (var importContext in query)
            {
                extractFromZip.ExtractFiles(importContext);
                casRecords.Add(importContext);
            }
        }

IterationWithLittleLinq.cs

private void Importy()
        {
            foreach (var fileInfo in files)
            {
                if(fileInfo.Extension.ToLower() == ".zip")
                {
                    importContexts.Add(new ImportContext
                                           {
                                               ZipFileName = fileInfo.FullName,
                                               Path = UploadPath
                                           });
                }
            }

            foreach (var importContext in importContexts)
            {
                extractFromZip.ExtractFiles(importContext);
            }
        }