diff --git a/.gitignore b/.gitignore
index 224994c..3fed684 100644
--- a/.gitignore
+++ b/.gitignore
@@ -22,3 +22,5 @@ go.work
 go.work.sum
 
 gh-commit-remap
+
+.DS_Store
\ No newline at end of file
diff --git a/README.md b/README.md
index 0fcfa7d..cd36769 100644
--- a/README.md
+++ b/README.md
@@ -28,4 +28,6 @@ Flags:
   -h, --help                       help for gh-commit-remap
   -c, --mapping-file string        Path to the commit map file Example: /path/to/commit-map
   -m, --migration-archive string   Path to the migration archive Example: /path/to/migration-archive
-```
+  -t, --number-of-threads int      [OPTIONAL] Number of threads(goroutines) to use for processing. 
+                                   Defaults to 10, cannot exceed 50."
+```
\ No newline at end of file
diff --git a/cmd/root.go b/cmd/root.go
index f94c337..3cb7e2a 100644
--- a/cmd/root.go
+++ b/cmd/root.go
@@ -18,6 +18,9 @@ func init() {
 
 	rootCmd.Flags().StringP("migration-archive", "m", "", "Path to the migration archive Example: /path/to/migration-archive.tar.gz")
 	rootCmd.MarkFlagRequired("migration-archive")
+
+	// Optional flag to specify the number of threads to use for processing
+	rootCmd.Flags().IntP("number-of-threads", "t", 10, "[OPTIONAL] Number of threads(goroutines) to use for processing. Defaults to 10")
 }
 
 // rootCmd represents the base command when called without any subcommands
@@ -34,20 +37,25 @@ var rootCmd = &cobra.Command{
 		}
 
 		// config to define the types of files to process
-		types := []string{"pull_requests", "issues", "issue_events"}
+		types := []string{"pull_requests", "pull_request_reviews", "pull_request_review_comments", "pull_request_review_threads", "commit_comments"}
 
 		archivePath, _ := cmd.Flags().GetString("migration-archive")
-
-		err = commitremap.ProcessFiles(archivePath, types, commitMap)
+		workers, _ := cmd.Flags().GetInt("number-of-threads")
+		if workers < 1 {
+			workers = 10
+		}
+		if workers > 50 {
+			log.Fatalf("Number of threads cannot exceed 50")
+		}
+		err = commitremap.ProcessFiles(archivePath, types, commitMap, workers)
 		if err != nil {
 			log.Fatal(err)
 		}
-
+		log.Printf("Processed files successfully, re-taring archive")
 		tarPath, err := archive.ReTar(archivePath)
 		if err != nil {
 			log.Fatal(err)
 		}
-
 		log.Printf("New archive created: %s", tarPath)
 
 	},
diff --git a/internal/commitremap/commitremap.go b/internal/commitremap/commitremap.go
index 27e6ef0..2f37af1 100644
--- a/internal/commitremap/commitremap.go
+++ b/internal/commitremap/commitremap.go
@@ -1,129 +1,180 @@
 package commitremap
 
 import (
+	"bufio"
+	"bytes"
 	"encoding/json"
 	"fmt"
 	"log"
 	"os"
 	"path/filepath"
 	"strings"
+	"sync"
+	"sync/atomic"
 )
 
-// Struct to represent a single entry in the commit map
-type CommitMapEntry struct {
-	Old string
-	New string
+const COMMIT_MAP_HEADER string = "old                                      new"
+
+type File struct {
+	FilePath string
+	Prefix   string
 }
 
-// Parses the file and returns a map of old commit hashes to new commit hashes
-func ParseCommitMap(filePath string) (*[]CommitMapEntry, error) {
-	commitMap := []CommitMapEntry{}
+// Parses the commit-map file and returns a map of old commit hashes to
+// new commit hashes using the old commit sha as the key
 
-	// Read the commit-map file
+func ParseCommitMap(filePath string) (*map[string]string, error) {
+	commitMap := make(map[string]string)
 	content, err := os.ReadFile(filePath)
 	if err != nil {
 		return nil, err
 	}
-	// Split the file content into lines
-	lines := strings.Split(string(content), "\n")
-
-	// Iterate over the lines and parse the old and new commit hashes
-	for _, line := range lines {
-		if strings.TrimSpace(line) == "" {
+	buf := bytes.NewBuffer(content)
+	if buf.Len() == 0 {
+		return &commitMap, nil
+	}
+	scanner := bufio.NewScanner(buf)
+	for scanner.Scan() {
+		line := scanner.Text()
+		// Skip adding the header to the map
+		if line == COMMIT_MAP_HEADER {
 			continue
 		}
-
-		fields := strings.Fields(line)
+		fields := strings.Split(line, " ")
 		if len(fields) != 2 {
 			return nil, fmt.Errorf("invalid line: %s", line)
 		}
-
-		commitMap = append(commitMap, CommitMapEntry{
-			Old: fields[0],
-			New: fields[1],
-		})
+		oldSha, newSha := fields[0], fields[1]
+		commitMap[oldSha] = newSha
+	}
+	if err := scanner.Err(); err != nil {
+		return nil, err
 	}
 	return &commitMap, nil
 }
 
-func ProcessFiles(archiveLocation string, prefixes []string, commitMap *[]CommitMapEntry) error {
-
-	for _, prefix := range prefixes {
-		// Get a list of all files that match the pattern
-		files, err := filepath.Glob(filepath.Join(archiveLocation, prefix+"_*.json"))
+// Processes the files in the archive and updates the commit shas
+func ProcessFiles(archiveLocation string, prefixes []string,
+	commitMap *map[string]string, workers int) error {
+	workerCount := workers
+	fileChannel := make(chan File, workerCount)
+	fileProcessWg := sync.WaitGroup{}
+	filesToProcess := getAllFilesToProcess(prefixes, archiveLocation)
+	totalFiles := len(filesToProcess)
+	processedFiles := make(chan File, totalFiles)
+	var processedFilesCount atomic.Int64
+
+	// go routine to print out the progress of the processed files. It also
+	// writes the processed files to a log file
+	fmt.Printf("Processed %d/%d files\n", processedFilesCount, totalFiles)
+	go func() {
+		f, err := os.OpenFile("processed_files.log", os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
 		if err != nil {
-			log.Fatalf("Error getting files: %v", err)
+			log.Fatalf("error opening processed files log: %v", err)
 		}
-
-		// Process each file
-		for _, file := range files {
-			log.Println("Processing file:", file)
-
-			err := updateMetadataFile(file, commitMap)
-			if err != nil {
-				return fmt.Errorf("Error updating metadata file: %v; %v", file, err)
+		defer f.Close()
+		for file := range processedFiles {
+			// Clear the previous line
+			// \033 is the ASCII escape character
+			// [1A moves the cursor up one line
+			// [K erases the line
+			// https://en.wikipedia.org/wiki/ANSI_escape_code
+			fmt.Printf("\033[1A\033[K")
+			fmt.Printf("Processed %d/%d files\n", processedFilesCount, totalFiles)
+			if _, err := f.WriteString(fmt.Sprintf("%s\n", file.FilePath)); err != nil {
+				log.Fatalf("error writing to processed files log: %v", err)
 			}
 		}
+	}()
+	// Starts a pool of workers to process the files
+	for i := 0; i < workerCount; i++ {
+		fileProcessWg.Add(1)
+		go func() {
+			defer fileProcessWg.Done()
+			for file := range fileChannel {
+				err := updateMetadataFile(file, *commitMap)
+				if err != nil {
+					log.Fatalf("error updating metadata file: %v", err)
+				}
+				processedFiles <- file
+				processedFilesCount.Add(1)
+			}
+		}()
+	}
+	prefixWg := sync.WaitGroup{}
+	// Seperate go routines to add the files to the channel
+	for _, file := range filesToProcess {
+		prefixWg.Add(1)
+		go func(file File) {
+			defer prefixWg.Done()
+			fileChannel <- file
+		}(file)
 	}
+	prefixWg.Wait()
+	close(fileChannel)
+	fileProcessWg.Wait()
+	close(processedFiles)
 	return nil
 }
 
-func updateMetadataFile(filePath string, commitMap *[]CommitMapEntry) error {
-	// Read the JSON file
-	data, err := os.ReadFile(filePath)
+// Updates each metadata file with the new commit shas
+func updateMetadataFile(file File, commitMap map[string]string) error {
+	var dataMap []interface{}
+	data, err := os.ReadFile(file.FilePath)
 	if err != nil {
-		return fmt.Errorf("Error reading data: %v", err)
+		return err
 	}
 
-	var dataMap interface{}
 	err = json.Unmarshal(data, &dataMap)
 	if err != nil {
-		return fmt.Errorf("Error unmarshaling data: %v", err)
+		return err
 	}
-
-	// Iterate over the commit map and replace the old commit hashes with the new ones
-	for _, commit := range *commitMap {
-		replaceSHA(dataMap, commit.Old, commit.New)
+	// Processes each of the different file types contained in the archive.
+	// The file types listed below are currently the only types that contain
+	// commit shas as a distinct field.
+	switch {
+	case file.Prefix == "pull_requests":
+		updatePullRequests(commitMap, &dataMap)
+	case file.Prefix == "pull_request_review_comments":
+		updatePullRequestReviewComments(commitMap, &dataMap)
+	case file.Prefix == "pull_request_reviews":
+		updatePullRequestReviews(commitMap, &dataMap)
+	case file.Prefix == "pull_request_review_threads":
+		updatePullRequestReviewThreads(commitMap, &dataMap)
+	case file.Prefix == "commit_comments":
+		updateCommitComments(commitMap, &dataMap)
+	default:
+		return fmt.Errorf("no supported rewrite found for file type: %s", file.Prefix)
 	}
 
-	// Marshal the updated data to JSON and pretty print it
+	// Pretty print the data
 	updatedData, err := json.MarshalIndent(dataMap, "", "  ")
 	if err != nil {
-		return fmt.Errorf("Error marshaling updated data: %v", err)
+		return fmt.Errorf("error marshaling updated data: %v", err)
 	}
 
-	// Overwrite the original file with the updated data
-	err = os.WriteFile(filePath, updatedData, 0644)
+	err = os.WriteFile(file.FilePath, updatedData, 0644)
 	if err != nil {
-		return fmt.Errorf("Error writing updated data: %v", err)
+		return fmt.Errorf("error writing updated data: %v", err)
 	}
 
 	return nil
 }
 
-func replaceSHA(data interface{}, oldSHA string, newSHA string) {
-	if data == nil {
-		return
-	}
-
-	switch v := data.(type) {
-	case map[string]interface{}:
-		for key, value := range v {
-			if str, ok := value.(string); ok && str == oldSHA {
-				v[key] = newSHA
-			} else {
-				replaceSHA(value, oldSHA, newSHA)
-			}
+// Fetches all of the files to update based on the file prefixes
+func getAllFilesToProcess(prefixes []string, archiveLocation string) []File {
+	var files []File
+	for _, prefix := range prefixes {
+		filePaths, err := filepath.Glob(filepath.Join(archiveLocation, prefix+"_*.json"))
+		for _, filePath := range filePaths {
+			files = append(files, File{
+				FilePath: filePath,
+				Prefix:   prefix,
+			})
 		}
-	case []interface{}:
-		for i, value := range v {
-			if str, ok := value.(string); ok && str == oldSHA {
-				v[i] = newSHA
-			} else {
-				replaceSHA(value, oldSHA, newSHA)
-			}
+		if err != nil {
+			log.Fatalf("error getting files: %v", err)
 		}
-	default:
-		// Unsupported type, do nothing
 	}
+	return files
 }
diff --git a/internal/commitremap/commitremap_test.go b/internal/commitremap/commitremap_test.go
index 550dc13..386b8fe 100644
--- a/internal/commitremap/commitremap_test.go
+++ b/internal/commitremap/commitremap_test.go
@@ -2,6 +2,7 @@ package commitremap
 
 import (
 	"os"
+	"reflect"
 	"testing"
 )
 
@@ -9,7 +10,7 @@ func TestParseCommitMap(t *testing.T) {
 	tests := []struct {
 		name        string
 		fileContent string
-		expected    *[]CommitMapEntry
+		expected    *map[string]string
 		expectError bool
 	}{
 		{
@@ -17,17 +18,17 @@ func TestParseCommitMap(t *testing.T) {
 			fileContent: `oldSHA1 newSHA1
 oldSHA2 newSHA2
 oldSHA3 newSHA3`,
-			expected: &[]CommitMapEntry{
-				{Old: "oldSHA1", New: "newSHA1"},
-				{Old: "oldSHA2", New: "newSHA2"},
-				{Old: "oldSHA3", New: "newSHA3"},
+			expected: &map[string]string{
+				"oldSHA1": "newSHA1",
+				"oldSHA2": "newSHA2",
+				"oldSHA3": "newSHA3",
 			},
 			expectError: false,
 		},
 		{
 			name:        "Empty file",
 			fileContent: ``,
-			expected:    &[]CommitMapEntry{},
+			expected:    &map[string]string{},
 			expectError: false,
 		},
 		{
@@ -38,6 +39,17 @@ oldSHA2 newSHA2`,
 			expected:    nil,
 			expectError: true,
 		},
+		{
+			name: "Skips first line (old .... new) and reads the rest",
+			fileContent: `old                                      new
+oldSHA1 newSHA1
+oldSHA2 newSHA2`,
+			expected: &map[string]string{
+				"oldSHA1": "newSHA1",
+				"oldSHA2": "newSHA2",
+			},
+			expectError: false,
+		},
 	}
 
 	for _, tt := range tests {
@@ -72,14 +84,9 @@ oldSHA2 newSHA2`,
 				}
 			}
 
-			// Check the result
-			if len(*result) != len(*tt.expected) {
-				t.Fatalf("Expected %d entries, got %d", len(*tt.expected), len(*result))
-			}
-			for i, entry := range *result {
-				if entry.Old != (*tt.expected)[i].Old || entry.New != (*tt.expected)[i].New {
-					t.Errorf("Expected entry %d to be %+v, got %+v", i, (*tt.expected)[i], entry)
-				}
+			// Compare maps for equality and length
+			if !reflect.DeepEqual(*result, *tt.expected) {
+				t.Errorf("Expected %+v, got %+v", *tt.expected, *result)
 			}
 		})
 	}
diff --git a/internal/commitremap/updatemodels.go b/internal/commitremap/updatemodels.go
new file mode 100644
index 0000000..32053af
--- /dev/null
+++ b/internal/commitremap/updatemodels.go
@@ -0,0 +1,95 @@
+package commitremap
+
+func updatePullRequests(commitMap map[string]string, pullRequests *[]interface{}) error {
+	for _, pr := range *pullRequests {
+		if prMap, ok := pr.(map[string]interface{}); ok {
+			// head_sha, base_sha, merge_commit_sha
+			if headMap, ok := prMap["head"].(map[string]interface{}); ok {
+				if headSha, ok := headMap["sha"].(string); ok {
+					if newSha, ok := commitMap[headSha]; ok {
+						headMap["sha"] = newSha
+					}
+				}
+			}
+			if baseMap, ok := prMap["base"].(map[string]interface{}); ok {
+				if baseSha, ok := baseMap["sha"].(string); ok {
+					if newSha, ok := commitMap[baseSha]; ok {
+						baseMap["sha"] = newSha
+					}
+				}
+			}
+			if mergeCommitSha, ok := prMap["merge_commit_sha"].(string); ok {
+				if newSha, ok := commitMap[mergeCommitSha]; ok {
+					prMap["merge_commit_sha"] = newSha
+				}
+			}
+		}
+	}
+	return nil
+}
+
+func updatePullRequestReviews(commitMap map[string]string, pullRequestReview *[]interface{}) error {
+	for _, prr := range *pullRequestReview {
+		if prrMap, ok := prr.(map[string]interface{}); ok {
+			// head_sha
+			if headSha, ok := prrMap["head_sha"].(string); ok {
+				if newSha, ok := commitMap[headSha]; ok {
+					prrMap["head_sha"] = newSha
+				}
+			}
+		}
+	}
+	return nil
+}
+
+func updatePullRequestReviewComments(commitMap map[string]string, pullRequestReviewComments *[]interface{}) error {
+	for _, prrc := range *pullRequestReviewComments {
+		if prrcMap, ok := prrc.(map[string]interface{}); ok {
+			// commit_id, original_commit_id
+			if commitId, ok := prrcMap["commit_id"].(string); ok {
+				if newSha, ok := commitMap[commitId]; ok {
+					prrcMap["commit_id"] = newSha
+				}
+			}
+			if originalCommitId, ok := prrcMap["original_commit_id"].(string); ok {
+				if newSha, ok := commitMap[originalCommitId]; ok {
+					prrcMap["original_commit_id"] = newSha
+				}
+			}
+		}
+	}
+	return nil
+}
+
+func updatePullRequestReviewThreads(commitMap map[string]string, pullRequestReviewThreads *[]interface{}) error {
+	for _, prrt := range *pullRequestReviewThreads {
+		if prrtMap, ok := prrt.(map[string]interface{}); ok {
+			// commit_id, original_commit_id
+			if commitId, ok := prrtMap["commit_id"].(string); ok {
+				if newSha, ok := commitMap[commitId]; ok {
+					prrtMap["commit_id"] = newSha
+				}
+			}
+			if originalCommitId, ok := prrtMap["original_commit_id"].(string); ok {
+				if newSha, ok := commitMap[originalCommitId]; ok {
+					prrtMap["original_commit_id"] = newSha
+				}
+			}
+		}
+	}
+	return nil
+}
+
+func updateCommitComments(commitMap map[string]string, commitComments *[]interface{}) error {
+	for _, cc := range *commitComments {
+		if ccMap, ok := cc.(map[string]interface{}); ok {
+			// commit_id
+			if commitId, ok := ccMap["commit_id"].(string); ok {
+				if newSha, ok := commitMap[commitId]; ok {
+					ccMap["commit_id"] = newSha
+				}
+			}
+		}
+	}
+	return nil
+}